It's not really that the Wii is the best version, Yojimbo, I'm just guessing that most people who are getting the Wii version don't have a 360 or PS3...so there's your answer.
That said, the Wii version will be good, as the only thing it doesn't have compared to 360 and PS3 is downloadable songs in the future...and even that could change sometime later...though it's not to be expected. The Wii version does have co-op and versus online play just like 360/PS3.
Also, the Wiimote plugs into the Wii guitars, which gives it Bluetooth connection, compared to 360's wired guitars and PS3's WiFi, plus the Wiimote gives the guitars rumble and sounds when you mess up through the Wiimote speaker. All relatively minor stuff, but that is something you don't have with the other versions, and if you've only got a Wii, well it's a pretty good GH3.
LEFT4DEAD411.COM
Bet with disolitude: Left4Dead will have a higher Metacritic rating than Project Origin, 3 months after the second game's release. (hasn't been 3 months but it looks like I won :-p )
