These picks are obviously not a complete list of all the great things that LEGO has to offer. They are based on my own experiences building them (at least many of them), general impressions from reading reviews, and from looking at the inventory/instructions from the sets. I don't think you can ever go wrong with any gift that involves LEGO. As an AFOL though, I field questions from parents all the time about what's the "best" set to get for their kid or relative. This list represents some of the suggestions I tend to offer.
Stocking Stuffers (Under $15)
Small LEGO sets can sometimes seem underwhelming, but these represent some of the better ones I believe are out there.
Collectible Minifigures - Widely available at major retail outlets, the CMF line continues to have wild popularity. The practice of 'feeling' packages to find that one specific figure is practically an art form, but I have never really been disappointed by any figure I have opened. Many of the characters are unique in the LEGO universe and these provide an excellent way to gather an army of citizens for any builder.
Emma's Karate Class - There are several Friends sets available in the $9.99 price range, but this is my pick for the most interesting of the bunch. There are some interesting pieces in this set and the karate outfit torso is a nice touch. My second pick at this price would be Mia's Magic Tricks (mainly because my daughter is in love with the little bunny).
Forest Ambush - Castle army building at its best, this set features four figures, a dog, plus plant pieces. It's obviously not a very substantial set, but it's the perfect addition to the collection of any Castle fan who wants to add a few more troops to join the battle.
Crawley's Claw Ripper - Like it or not, CHIMA appears to be here to stay for awhile. One of my nephews has become obsessed with the theme, so I'm getting a much closer look at some of the sets than I had originally planned. The figures in this theme really are great and extremely detailed. This vehicle is surprisingly durable and makes for a pretty funky little battle vehicle.
The Average gift range ($15-40)
This is where the bulk of my LEGO purchasing is done for gifts, so I will be offering quiet a few options here.
Spider-Man: Spider-Cycle Chase - I'm pretty happy with all of the Super Heroes sets in the $20 range. They all have a great selection of figures and interesting parts. This set gets my pick because I love Spider-Man and the car is just plain awesome. It's extremely sturdy and the hover conversion on the wheels opens up two avenues of play. Venom and Nick Fury are just great figures to have as well.
Eris' Eagle Interceptor - Still my favorite set from the CHIMA line, no question about it at all. This set has tons of articulation, great figures, and a very appealing color scheme. Even if you have an only passing interest in the theme, this set is a great build and the finished product is tons of fun.
The Golden Dragon - Ninjago remains wildly popular. This is a very nicely done set and I'm pretty sure you would have a hard time finding a boy who does not love ninjas and dragons. This has also been pretty deeply discounted for the past several months, making it a steal right now at the price it's listed at with many retailers.
Downtown Bakery - Food. Lots of food. I love sets that help me build up a menu for my LEGO figures to dine on. Aside from that, this really is a nice looking set with a good selection of parts. I have a feeling the Heartlake Pet Salon will get more love, but I've always like bakeries more than puppies.
Creator Tree House - What kid doesn't love a tree house? There's just so much detail packed into a $30 set here. It's the tree fort I always wanted to build as a kid, but never had a nearby tree big enough to put it in. The brick-built dog is also a great little touch.
Flatbed Truck - I'm a big fan of most CITY vehicles that are NOT related to the police of fire aspects of the line. I like good utility vehicles that you would commonly see driving around town each day. My only gripe about the set is that the woman should have a "freaking out" face printed on her, since most of my run-ins with tow trucks have not been under happy circumstances. On a similar note, the Monster Truck Transporter is pretty sweet as well.
Mini Backhoe Loader - I had very few Technic sets growing up and I don't really buy many of the sets from the line even now. I mainly just look at the instructions to see how the assemblies work, with the goal someday of incorporating moving parts in to some of my MOCs (have not tried that yet, it's on the list). This set really intrigued me though. It has a ton of cool features showcased by multiple points of articulation. For the more technical builder, I see this as a great entry-level set for Technic products.
Stagecoach Escape - Yes, the Lone Ranger movie was a flop at the box office. It doesn't change the fact that this is a great set with a ton of figures and three horses. It's fun to build and my daughter loves to play with it. I basically ignore the TLR connection and just like to think of this as a really good western set.
LEGO Play Book - While it's not a set, I think this book is just full of awesome and should be in every LEGO fan's collection. This thing is packed with some amazing ideas for kids and adults. DK publishing does an excellent job on these books.
The DeLorean Time Machine - I'm a child of the 80s, so it's probably no surprise that this set was a day one purchase for me. While there are some flaws with the model (such as the outline pieces that represent the edges of the windshield), I still believe this is a very well done set. Being able to easily alter the model to reflect the trilogy is an awesome idea. The finished product really feels so much better than the stock images LEGO put out for this. A snap buy for any AFOL who grew up in the 80s.
The Bat vs. Bane - While most young kids have probably not seen Nolan's gritty trilogy of Batman movies, I still think think this set offers a lot for any fan of the Dark Knight. At the top end of this price range, I found this to be a much better deal than the Malibu Mansion Attack in the Super Heroes line.
For the good kids ($40-80)
This is also the range where you start getting to sets adults will really enjoy more as well, since they offer more of a challenge and are typically more detailed.
Dragon Mountain - Easily my favorite set from the latest Castle line. The dragon is a great piece, but the actual structure itself is pretty darn cool as well. I think LEGO hit it just right with this one.
Spider-Man: Daily Bugle Showdown - I've raved about this set before, and it's probably one of my favorites from the second wave of Super Heroes sets in the mid-range of the line. The building itself is very impressive and Dr. Doom's ship is a fun little build. Good set is good.
Gorzan's Gorilla Striker - Two words: Banana Gun. I have an odd fondness for mech-style sets. I think they have some cool play features and usually have great parts in them. This is a pretty quirky set, but I think it's a ton of fun and worth picking up for any CHIMA fan.
Dolphin Cruiser - This set might even appeal to builders who don't even like Friends very much. The lift off design to access the lower cabins gives you the full range of play with the boat and the color scheme is very pleasing. I've actually considered adding a marina to my planned layout simply because this boat exists. Easily the best Friends set yet.
Turtle Lair Attack - While I don't think it can beat the actual full size version made for regular figures, this is still a great set. I only wish it came with all four turtles. There are plenty of little play features tucked in here and it has several very useful parts.
Family House - I don't think you can ever go wrong with the houses made for the Creator line. All of them feature some unique and creative designs that make them stand out. The two-toned roof creates a nice effect, as do the many large windows. I especially like the use of the light brick to help highlight the large interior space of the home.
Temple of Light - I have always enjoyed the designs for the major Ninjago sets that are location-based. This one provides you with an excellent looking mech and a pretty substantial building. Kids should love this because there is a wide variety of characters and giant robots are always a big hit.
For the "amazingly good kids/spouses" ($80-200)
This is the stuff that growing up as a kid my parents would have picked as a "big present" under the tree. These sets are the ones fans young and old will enjoy.
The Lion CHI Temple - This thing is pretty epic and serves its purpose well as the flagship of the CHIMA line. Packed with figures and play features, this is just an amazing set. Get it for the kids or get it for yourself. I think most builders will just love this one.
Republic Gunship - It's not the first version of this iconic vehicle to be made in brick form, but it's very easy to see why LEGO keeps rehashing this one. This latest version is very well done and makes an impressive display piece for fans who just want to add to their fleet of Star Wars ships. Even though I'm not a big fan of the prequels, I greatly enjoyed the Clone Wars animated series and this ship is featured heavily there. It's one of the few Star Wars sets this year that feels like a "must buy."
Jabba's Sail Barge - While initial impressions of this set were a little mixed, I think it turned out much better than many Star Wars fans initially thought it would. The barge uses a number of interesting building techniques and I think a Jabba figure is something every kid will love. That said, I still feel it's a little overpriced at regular retail. Look for sales on this one.
Palace Cinema - The modular building line is pretty much a staple of my collection at this point. I loved being able to add another corner building to my collection and this set just looks great. I still think having a windows in a movie theater is a little stupid, but I have been playing with a few different methods to replace them. It's not my favorite of the series, but it's a solid addition to the theme by LEGO.
Arkham Asylum Breakout - The new version of the classic Batman I set just blows its predecessor out of the water. I love this set and it's probably my absolute favorite from the past year. Several of the villains are exclusive to this set. It's a beautiful building and I just love the architectural features. This set will be a classic for years to come and I can't think of a good reason why you should not have it. Buy it. Buy it now. Just blame me for having to spend the money. I can live with that.
The Haunted House - While technically a 2012 set, I still felt compelled to put this on here because I truly do believe this is one of the best sets LEGO has available right now. This mansion really has it all. With a richly detailed exterior and interior, there are hours of enjoyment to be had with this set. I was extremely happy to add this to my personal collection and I believe this will easily fall in the category of sets that are remembered for years to come.
For the "Can you buy presents for me?" crowd ($200+)
This is the stuff that's for the really good kid/adult on your list.
Ewok Village - While the Death Star remains the top end of the Star Wars line, this new entry does a good job of recreating a key location of the original trilogy. Featuring 17 figures, you get a pretty substantial collection of OT characters here. As you would expect, there are a ton of play features in this. It's also a pretty detailed build, using a ton of different techniques to create the trees that hold up the village itself. I'm not a fan of most smaller Star Wars sets, but I always feel that LEGO gets it right when we get to the higher end of the price range for sets.
Sydney Opera House - I was lucky enough to see this over the summer at Brickworld, and I think it's an excellent addition to the landmark series of large sets. A variety of techniques are employed to create this iconic building. The finished product is very impressive and will wow anyone who sees it in person. The only downside is that the footprint for this set is pretty large, making it very difficult to find a place to put it on display.
That about covers it for what I feel are some of the best of the best LEGO has out there this year. Still, like I said at the start, I don't believe a bad LEGO present exists. It's pretty much guaranteed that any child I'm shopping for this year will be getting bricks for the holidays.