Buy:
Brawl
Twilight Princess
Skyward Sword (haven't done a play through yet although its apparently great)
Mario Kart Wii (pretty good online play if you're going to do that)
Metroid Prime 3
Donkey Kong Country Returns
Super Mario Galaxy 1 & 2
Resident Evil 4
New Super Mario Bros. Wii
Rent:
Kirby Return to Dreamland (decent but good only for one play through)
Sonic Colors (best sonic game to come out since sonic and knuckles)
Wii sports Resort (its buy able but only if you plan on playing it a fuckload with others)
Download:
Anything Legend of Zelda
Mega Man (the recent one ((10 I think it was called?)) was apparently pretty good, might check that out)
Super Mario RPG: Legend of the Seven Stars (paper mario basically except harder somewhat)
My Pokemon Ranch ( if you want the free Mew but its hard to get; you have to upload 999 pokemon using just diamond and Pearl. other than that its useless)
Don't ever get near:
all Shovelware (carnival games, multiplayer "party" bull, etc.etc)
Wii Music (a waste of time, literally)
PBR (its terrible. only useful for the items and the event pokemon, which you cant transfer to gen.5 anyway)
Anything Raving Rabbids
ANY sports games, EA ones for sure (All Maddens from 10 onward are unplayable due to fucking GOD AWFUL player design and shitty textures. Half the original madden modes are gone and you cant edit the players. Almost every EA Sports game is like this on the Wii. I don;t think FIFA is, though... I'm not sure.)