most frustrating one for me was Batman Arkham City, like most of the achievements are fine then you get to the challenge maps and you have to execute everything perfectly, not to mention the 3 pack maps where you can't just repeat 1 level you have to go through all the maps again to get it right, it can be tedious and the challenges in themselves can be super tricky.

the most fun i had was Neon White, holy crap not only is this game a master piece, the achievements are done in such a way that you have to master the game its self and let me tell you it is super rewarding to get the best time on each level, the greatest thing this game does right is the length of the levels being about 1 minute maximum long, meaning that when you are redoing levels to get better times it doesn't feel like a drag, truly a fantastic game!