I have finished (not 100%, who 100% games these days):
NSMBU
NSLU (great standalone DLC)
Lego City
SM3DW
DKC TF (favorite game on Wii U)
AC 3 (this game starts slow but it was my first AC so I don´t get the hate, I liked it)
CoD BOs 2
Playing:
W101 and Zelda WW HD with some MK8 here and there
To finish:
Pikmin 3, ZombiU (too scared, lol), Splinter Cell BL, MK8, Rayman Legends and Darksiders 2. I need to play more NintendoLand, great game but no time and so many games to finish.
To get: Bayo/Bayo2, Deus Ex, Batman AC and AO, Hyrule Warriors, Lego Marvel, Lego The Movie, NFSMWU, ME3.
Note: For some people not getting into Wii U because it is underpowered, most first party games look great and are 60fps if not solid 30fps, even most 3rd party games are solid 30, like Deus Ex, Batman AO, NFSMWU, ZombiU, Splinter Cell BL, Rayman Legends (1080p60), Mass Effect 3, AC 3. If you don´t mind 720p and aliasing in some games you are ok, for me games look amazing and I have a PS4.