Wow, this poll is quite old. A lot has changed in 2 years. Back then, I would of said the xbox 360. The Wii to me has always been not a true player in the current gen, simply because 1. the library of quality games is incredibly slim and 2. The 360/PS3 are far more superior. You won't see Assassin's Creed or Batman Arkham Asylum or Fallout 3 on the Wii.
The 360 started off incredibly strong with the best (and still best) online multiplayer experience: With the release of Cod 2, Gears of War, Halo, and the giant block buster Modern Warfare, it was the system for hardcore gamers.
However, over the past two years, franchise fatigue has started to take in effect with Halo and Gears, and even to the giant elephant Call of Duty. Microsoft was starting to lose their exclusives like Bioshock, Mass Effect, while PS3's crazy price (around 700ish I believe during launch) started to drop. As the years went by, PS3's more powerful hardware started to become evident, as the 360 started to hit its limit. Along with increasing it's gaming library, the PS3 right now is top dog, recently outselling the 360 over the past months.
So, I vote PS3.