I got both roughly 3 years ago. I've used the PS3 far more, the Xbox360 I only got because there was a good deal on including some exclusive games that I wouldn't get to play otherwise (PGR4, Forza2, Fable2, Halo3/Reach, GOW2 etc). In nearly 3 years I've only actually played two games on the Xbox, PGR4 and Forza Horizon, so in hindsight I shouldn't have bothered.
PS3 is much better IMO, more powerful, plays bluray, built in wifi, quieter (I put the Xbox on for the first time in over a year to play FH and my wife thought there was something wrong with it because it is so loud!). Although to be fair I do think the XB360 pad is better.
Obviously both are dwarfed by PC in terms of my gaming hours by at least 10:1