You all do of course realize that MS and XBL are American made/owned products (not counting that like all systems are produced in China :P), so going by most people's need to "support local brands" then Americans will generally pick Xbox over PS.
The reverse to this is true as well. In Japan, PSN and Playstation itself are probably like 80%+ more popular than Ms and XBL, because Japanese people support Japanese products as well.
What should truly matter however, is which network (XBL or PSN) is more popular worldwide, counting every region. Find me those numbers if you want to impress me about what's more popular. Otherwise, this really is blatant trolling for stating an obvious fact in an obvious region to try and get people to argue about what's more popular. World stats are all that matters for popularity.
Pretty sure I posted somewhere in this thread that world wide numbers PSN surpssed XBL by around 12 million...2 years ago.