I'm aware that I'm probably in the minority, but in my experience, the 360's reliability is much greater than the PS3's. I had a launch 20GB PS3 first. The blu-ray drive in it failed exactly one week after the one year warranty expired. I called Sony and of course they wouldn't give me a break and wanted me to pay $200 to get it fixed. I did and they sent me back a refurbished 40GB which just about sent me through the roof.
I kept it for about 6 months before eBaying it. I then purchased a brand new 80GB. Exactly 1 year and 5 days later the exact same thing happened - it stopped reading discs because the drive broke. Once again, Sony would not honor it. They said I'd have to pay $150 to get it fixed. I took it to Gamestop and actually got full price because they didn't check to see if it reads discs.
I ended up scoring a new slim PS3 about 2 weeks before they even launched. Guess. What. It failed 2 days ago - stopped reading discs. I called Sony and naturally, they would not honor it. It's out of the one year warranty by 2 days and they wouldn't do it. That's 3 PS3s breaking within a week of the warranty having expired and Sony didn't fix a single one of them.
Granted, I'm sure my particular case is very rare. I've actually never had a 360 break on me, but both systems do clearly have problems. Of course, I remember a good many people having issues with PS2s back in the day, and I used mine every day for 4 or 5 years and it never acted up once.