Seeing as how the games so far have sold the best in the US, I expect the 360 or PS2 to do the best. The Wii has a good chance of beating the PS2, and a very slim chance at beating the 360, but the PS3 is pretty much guaranteed to sell the least.
This is the first Guitar Hero game on a Nintendo console, so it's still a mystery how well it'll do.
(edit: wtf, there are two separate PS2 games called Guitar Hero 2 and Guitar Hero II on the million sellers list, both with different numbers and publishers, yet the same box art)







