SSBB without a doubt. I recall a gamefaqs poll, in which (which game are you most excited about. Mario galaxy and super smash bros brawl were 2 of the games listed (look about 2 months back). Smash bros brawl had about 65% while galaxy had about 14% of. You go on gamefaqs and the brawl board is the most active board on the site. It's incredible the amount of sales this game is going to drive. I see 2 million in the first week no doubt.

i think halo 3 will have a higher attach rate than ssbb but by the time this gen is over and wii's installed base is several tens of millions higher than the 360's it'll push brawl over. i think without a doubt halo 3 will sell better than halo 2. but ssbb with all its new features and online with a userbase that is gonna be several times bigger than the GC's its gonna blow ssbm sales out of the water.

for halo 3 vs. some of wii's future big games (including some probable but unannounced games I predit...
halo 3: 10-11 million
ssbb: 11-13 million
smg: 11-13 million
wii fit: 5-15 (big range cuz i think it'll be popular but i have no idea if it'll hit crazy status)
mario kart: 9-10 million
if an online wii sports 2 comes out: 18-20 million
if a really good full length pokemon rpg comes out: 14-16 million

smg, ssbb, and mario kart are not so hardcore like halo 3 that only gamers are gonna buy them, casuals will buy too. wii fit will probably be eaten up by casuals and some non-casuals. if nintendo makes a full length pokemon game on wii and its as good as the portable ones pokemon fans will go into a craze and things will get nuts. and if there is a wii sports 2 that is online and offers improved sports from the first with new sports too it will absolutely sell a ton to every wii audience/demographic. halo 3 is the big picture on the 360, on the wii it would be just one of many.

I've seen a couple of comments regarding Halo 3's lack of legs here, and I have to ask, where have you been these last 6 years? If anything, Halo games have had unbelievable legs. Halo 2 still charts as it was mentioned, and Halo remained a top 20 seller well into 2004. There's no reason why Halo 3 won't exhibit similar legs.

Why were Halo and the original Super Smash Bros being compared? They're on totally different consoles. I think in the long run SSBB has a very high chance of selling more than Halo 3, simply because of the fact it's a game that will last ages and ages because of its Multiplayer/Online features, as well as that awesome Stage Building thing. But dunno, it might sell as fast as Halo 3 did when it got released, there's huge hype going on for it because of the great features that were'nt in SSB and Melee.