2D: Super Mario World
3D: Galaxy 2
Galaxy 2 is a game that I didnt really know what to expect going into it, because Galaxy 1 was already so good. The level design in this game is straight-up genius. Every. Single. Level. throws something new, novel, creative, and fun at you and never lingers on any one gimmick long enough to feel like it overstated its welcome. The 2-player co-op with P2 controlling the Luma using the Wii Remote pointer was surprisingly fun, and I am beyond thrilled that Nintendo decided to do something similar in Odyssey.
I fucking love Super Mario Galaxy 2. I wasnt sure what my favorite was before writing this post, but I think I can say Galaxy 2 is my all-time favorite now.