Well i have a wii and its time i got some games for it. I currently have Wii Sports, Wii Fit, Mario Kart Wii and SSBB. I prefer action, adventure and shooting games mostly. At the moment im thinking of getting Super Paper Mario or RE4 (Resident Evil 4) but i dont know which one to get >.>
Out of all the games I own on the Wii, i think the best is Super Mario Galaxy. Its a fantastic game, and probably the best mario game i've ever played. No more heroes is also a great game and really funny. If you have your Wii online, you should also have a look at some of the Virtual Console and Wii Ware games on there. There are some really great classics on there.
Theres also quite a few great looking games due to come out this year. The Conduit will be a great FPS hopefuly and Madworld looks to be one of the first really mature games to come out on the Wii. The new Punch-Out also looks good to me. I also read theres rumoured another Zelda game may come out for the Wii, though that wont be for a long time (Plus i'd be surprised if Nintendo did bring out another Zelda game for Wii, rather than save it for their next generation console)
Contrary to popular belief, there are loads of great games on the Wii.
- Metroid Prime 3: Corruption; - Super Mario Galaxy; - The Legend of Zelda: Twilight princess; - Guitar Hero 4: World Tour; - Resident Evil 4; - Super Paper Mario; - Call Of Duty: World At War; - Disaster: Day Of Crisis; - Deadly Creatures (surprisingly good); - No More Heroes; - Okami; - The House Of The Dead: Overkill.
And for WiiWare:
- Lostwinds; - Toki Tori; - Tetris; - Mega Man 9.
Especially the first 4 are musthaves for a Wii-owner, but it all depends on your own taste of course.