Obviously the fanboys of each will bias towards them.
Personally though, I have a wii, PS3 and 360. Truthfully the PS3 is much, much better for my purposes.
It had an internet browser way before the 360, has slightly better graphics (visible in PS3-only games) and has better hardware. Also the online play is completely free yet equally as useful and works fine. Plus I can stream movies from my PC to it or I can play movies directly from my USB hdd. Oh and also the ps3 actually allows the installation of another OS (linux). Not to mention it already has blu-ray too. Microsoft can only continue in future by using blu-ray in a new xbox or the 360, they have to switch eventually.
Anyway, in my honest opinion, PS3 is better of the two. You'll find that 90% of the people who argue for xbox don't even have a PS3.