Surprise, surprise! My favorite Wii game of 2010 is the one I (likely) wrote about the most last year: Kirby's Epic Yarn.
here's a number of them) that I won't bore you by going over it again in this one.
What I will say is that this charming platformer made me smile more than any other Wii game I played all year. Sure, a few of its contemporaries came close--Donkey Kong Country Returns and Super Mario Galaxy 2 come to mind, as does Ivy the Kiwi--but none were able to topple Kirby in terms of providing pure, unadulterated fun.
That's not to say Kirby's Epic Yarn is perfect--it's too easy by half, for instance, and it has a few, niggling control issues (namely while using the train transformation)--but it's perfect enough to be not only my favorite Wii game of 2010 but to be among my favorite games (regardless of genre) of this entire generation.
See also: 'New Super Mario Bros. Wii: One of my favorite Wii games of 2009'