Wii has a lot of great games, although Mario is without a doubt very popular.
My favorite Wii games:
Another Code R
Pandora's Tower
Xenoblade Chronicles
All three of these were hated by Reggie and didn't came to the US or came late and limited in the case of Xenoblade.
Other good games:
Monster Hunter Tri
Resident Evil 4
Super Smash Bros Brawl
Wii Sports Resort (Nintendo needs to bring back Wuhu Island)
Umbrella Chronicles (shockingly good on rails shooter)
Mario Kart Wii
Twilight Princess
Fire Emblem:Radiant Dawn
Beat the Beat: Rhythm Paradise
Muramasa
Metroid Prime 3
Zack&Wiki