I like the Uglies series by Scott Westerfeld. I just looked up that series as I hadn't heard of it, and it sounds great *adds to reading list*
probably my least favourite genre next to paperback romances but i have been enjoying what i have read of the gregor the overlander series :<
All the Tamora Pierce quartets, The Hunger Games, Divergent, Matched, CHERUB, The Kane Chronicles and Maximum Ride.
Mine would have to be the series by Gary Paulsen that started with Hatchet, about the boy Brian, who survives a small plane crash and has to learn to survive alone in the wilderness of Canada. I don't think as many books made such a deep impression on me in this genre. I loved his book Dogsong, as well. I always tended to like books about running away, surviving in the wild, and ones about dogs, such as Where the Red Fern Grows.
Harry Potter and The Hunger Games. I also loved the first Mazerunner book and the first 2 Divergent books but I felt they got a bit boring after that and never got around to finishing The Death Cure or Allegiant. John Green books are great for light reading and while I do really enjoy them, they're quite over hyped.
Probably Harry Potter. It's sort of an obvious choice, but it's a great series. I used to be a lot more into YA a few years ago, but I got kind of sick of the whole genre so I'm not sure anymore.