Wii: Around the end of Sept
DS: Mid-October
PSP: Around the end of Sept
PS3: Late October
360: Early to mid October
Those are my guesses for all mentioned events, so I guess I would say a toss up between Wii and PSP.
PS - I just did a quick glance at the numbers nothing deep.
Edit: To use your format...
Wii -> PSP -> 360 -> DS -> PS3
Just gave the Wii the benefit of the doubt because it has more buzz at the moment, the numbers I looked at make me think it will be close either way.