Reasons behind the 360 > Wii > PS2 > PS3 logic
360: Largest user base means most gamers and most people that just want Madden. The majority of people that just want to play Madden will have the 360 and that's what they will buy it for. There's also achievements to factor in. Madden is a quick 1000 gamer points and there are a good amount of people that will pick the 360 version just because they can make their score a little bit bigger. Also, Xbox Live is a huge factor too.
Wii: The Wii has the second largest user base with unique controls and features. Every person I know that has either PS3 or a 360 and a Wii wants the Wii version. People are intrigued by the new controls and little features like accurate weather appeal to people. Also, Madden for the Wii doesn't look too bad and that will help push people that own an HD system and the Wii in the Wii's direction. Mix all that in with a large user base, and the Madden for the Wii will do well.
PS2: There are still a lot of active PS2's out there and I would imagine a lot of those just get used for Madden and GTA. I think the battle for the #2 spot will be pretty bitter but even with the numbers I think the PS2 will lag behind. A lot of the people that buy Madden every year already have a Wii, PS3, or 360 and they just aren't going to buy the PS2 version if they have those (not as good looking, no online, no achievements, no special features).
PS3: The PS3 has the smallest user base and there are nasty (untrue I believe) rumors that the PS3 version doesn't run as smoothly as the 360 version. While the rumor that the PS3 version runs at 30FPS while the 360 version runs at 60FPS might reach your typical Madden freak, the fact that it's complete bull probably won't. Add to the mix that the PS3 doesn't have achievements and I just don't see this version doing well (compared to the others, it's still going to sell like Madden--see what I did there 
).
