Sony - Fanboys (honestly, I buy an average of 50 games/year; I have 3 360s... I would buy a PS3 - because I can afford - if it wasn't for what I read on the internet!).
Nintendo - My gf keeps playing the damn DS.
MS - RRoD - but never really affected me - which I know it was a problem.
I mean... I don't usually read ppl with 360's with sigs like "360 is the future"; "360 unttaped potential"; "360 will rule the world". Cockyness isn't cool.