Final Fantasy X-2 hd 

Hmm... I think Pokemon Y

Realistically? Mario Kart and Smash Bros... and they'll probably be among my most played in 2015 as well.

That doesn't mean they'll be my favorite experiences; Monolithsoft's X and the Fire-Emblem - Shin Megami Tensei crossover might eat my life too, as well as any number of RPGs.

This definitely, but that's only because it's coming out before Smash Bros. It's because these two games are coming out this year that I got a Wii U in December.
@Slade6Alpha, that's the best picture of Typhlosion I've ever seen!

Hard to say at this point. It could be any number of things for me, as there really are a lot of releases I know I'm going to play the crap out of. Titanfall, ESO, Destiny, Dragon Age Inquisition, Witcher 3, Halo 5......

Of course the earlier releases will have a leg up, so if I had to guess I'd say it'll probably be between Titanfall and ESO

If X comes out it will be that. Otherwise mario kart 8.