I was in the same position a few weeks ago. My personal Choice would be Super Paper Mario, hands down, It's one of the three Great Wii Games out so far (the others being RE4 and Zelda)
First off, it's not a fun multiplayer game like Mario Party 8 is, I'm sorry to say it's best enjoyed alone.
Second, it plays like an RPG, not a platformer. This is a Plus for me, but I don't know your taste in games.
Third, It's a great game to play through, it has an EXTREME resemblance to Zelda TP, just the way it's designed, maybe it's the level design? Well, I think they based this game off TP, and it has nothing new to add to the industry or anything, but everything about it is good, if not a bit boring.
Those are 3 possible problems... Despite those, it's a fantastic game and you should definitely buy it =D