I have a PC and a PS3
PC has been my life since i was like 5, so i tend to stick to PC gaming.
I recently got the PS3 because there are certain games that i feel are better on the PS3 and some games can only be played on consoles
Like - Sports games - Fifa is epic on console, on PC its not bad but i prefer it on console.
Final Fantasy (Usually only on PS2/3 with the odd 1 or 2 on PC) - Love this series
MX vs ATV or any bike games on console are good fun, PC doesnt have many bike games that are actually decent.
Fighting Games - Mortal Kombat, Tekken etc.. Arcadish games - Sonic, Mario - etc.. i prefer them on console, it gives you that feeling of playing tv games with cartridges as a kid just with improved graphics and not cartridges...
I spend 90% of my time on PC, Which does a million things more than the PS3 ever will, even while it is older than what id like.
The PS3 is also useful to me because i needed it to watch blueray 3D discs on my telly and didnt want to spend money on a bluray 3d player that cant play games. so was a win win when i bought the PS3.