I actually borrow my brother's 3ds, and I only bought 3 games but he has a lot so here's our top 10 combined:
01. Fire Emblem: Awakening [145:15] *
02. Kid Icarus: Uprising [134:19]
03. Pokémon X [72:27] *
04. Mario kart 7 [46.12]
05. Animal Crossing: New Leaf [30:17] *
06. One Piece: Unlimited Cruise SP [23:15]
07. The Legend Of Zelda: Ocarina Of Time 3D [22.59]
08. Pokemon Mystery Dungeon: Gates To Infinity [21.36]
09. Mario Tennis Open [14:07]
10. New Super Mario Bros. 2 [10.09]
* My games
NNID/PSN: Kung_Kjartan