I'd say all three have brought about an incredible amount of creativity with developers. The Wii had a new control scheme and cheaper development costs than the other consoles, allowing small developers to make creative, fun games that often see success. The 360 has XBLA, which has allowed games to be made for very cheap, and if the game is good, it's possible for it to make millions of dollars with a small development cost. And the PS3 is about to bring LittleBigPlanet, which could very well be one of the best games this generation. Besides that, the PSN allows developers big and small to make money on low budget games.
Not only that, but all three consoles have brought a massive variety of quality games in a short amount of time. Easily the best generation yet.
