If I had to guess, the Wii probably outsold both and by a big margin. I figure this becasue it has the biggest userbase and also because old school Megaman was a big part of the NES. So I feel that many of the old school NES fans have made their way back or stayed all along with Nintendo.
I think the PS3 version did second best despite being #3 in console sales, still far behind the Xbox 360 because the PS brand has also been around now for quite a while and if old school Nintendo fans moved on to another console years back, it was the PS.
And Xbox 360 probably did the least because they're the newer brand and I think they might have more younger gamers, under the age of 25 and even who might not be as familiar or care as much about Megaman. I'm not saying that's the case with everyone so no need for anecdotal evidence.
I'll come up with something better eventually...
