Over the generations, my gaming systems of choice have gone PS, PS2, Xbox 360, and now PS4.
Why the switch back to PS? Because my 360 consoles—all four (five?) of them—repeatedly broke down due to unexplained reasons. I'm almost embarrassed I stuck with Xbox at all, but I had a large game collection and wasn't about to liquidate it for pennies on the dollar to switch to PS.
Trying to get Microsoft to honor the quality of their product was like trying to nail a bucket of water to the wall, and their customer service reps were just awful to deal with. So many frustrating phone calls and so much wasted time, and it was like those damn things had a doomswitch in them that flipped immediately after the warranty date passed.
One time, I did end up getting an executive (a real one, not a pubescent "customer account executive") via email after some extreme persistence, and he agreed to get me a free refurb in exchange for the broken one. They sent the refurb, and I sent the broken machine, and all was well for a few weeks, until I noticed on my credit card statement that they had charged me like $200 for the refurb.
Why? Because they were claiming the machine I sent back—which I'd owned since it was NIB—had been tampered with. I ended up receiving it back via UPS shortly afterward, and when I tried to turn it on, it was even more broken than before. Originally, it just wouldn't read discs. When it came back to me, it wouldn't even turn on. No one could give me a straight answer about how it had been tampered with, and I knew for a fact I hadn't done anything to it. It took even more phone calls and emails to get someone to refund the $200 they'd charged me and take the broken machine back.
So, yeah, PS this time around, because FFS, life is way too short to deal with that kind of nonsense again.
TLDR: PS4 because of very negative quality and service with XBox 360.