i really like plat former games (2D and 3D)
well, the obvious ones are the mario games, specially super mario 3d land, that said, super mario maker is tons of fun even if you dont make levels (i havent even touch the level editor and have like 30 hours on it), new super mario bros 2 is OK, its levels are a mixed bag from good to absolutely horrible, but its still a good game.
then you have rayman 1 and 2 (the DSi version of the 1st one is on the eshop, beware though, it makes a sound and takes a picture it doesnt save of you every time you save, even with the volume turned all the way down; the second one is also on DS, but get the much better 3DS version)
gunman clive 1 and 2 are both amazing, the first one is short and not all that replayable (played it 3 times with each character on one sitting after beating the game once on the train) but its really good, the second one is a little longer and a little better; if you are wondering what they are about, its like megaman but with less complicated, more contra-like combat.
ANYTHING by inticreates, they are an awesome company and they made a ton of great games, a lot of which are on the 3DS.
megaman legacy collection has all 6 NES games plus a whole bunch of extra content which you may like if you already love the games.
terraria, its not really a platformer, its more 2D minecraft with a bigger focus on combat and town building, with a bit of platformer in it.