Well, Xenoblade Chronicles is the best game on the Wii, even if you include the Galaxy games.
Then it's a toss-up between The Legend of Zelda: Twilight Princess and Metroid Prime 3: Corruption. Okami is also a very good game, I hope it gets a sequel at some point as I don't care about Kamiya's other games. For such a casual console, most of the games I liked for it could be considered "hardcore" or "niche". The only other games I'd put in the same league as the ones I just mentioned are the Super Mario Galaxy games (if you were wondering where I ranked them). I never played Resident Evil 4 or Donkey Kong Country Returns, but I think I'd like those as well (Tropical Freeze is one of my favorite Wii U games).
Mario Kart Wii was a bit of a letdown after Double Dash (the online was good though), but I stil enjoyed it. And I disliked the entire Wii-series of games, I'm glad they've abandonned that.
"The strong do what they can and the weak suffer what they must" - Thoukydides
