The PS1 and the PS2 are really quite crappy, but as Joe said, the PS3 "seems" to be OK. The 360 seems like it's just waiting to break down - the thing is loud as hell too - so you basically need to go out and buy that peripheral cooling unit to keep the machine from blowing up. However, the original XBOX is like a concrete block. It may not be the prettiest thing, but it is tough. The only major problem with the XBOX, that I know of anyway, is that Microsoft - in their infinite wisdom - decided to contract out 3 different manufacturers for their disc drives. The worst is the Thompson drive, which is the one I have and was the first drive manufactured for the XBOX. The Thompson drives tend to konk out and can't read most CDR media and they also will give you the dreaded "DISK ERROR" screen. Then Microsoft started putting in Phillips drives and that was a minor improvement. However, the Samsung drive is considered the best of all. It won't give you the "Disk Error" screen and it can read pretty much all media.
I don't really have too many problems with my Thompson drive though. I think it was Burnout Revenge or Gotham Racing 2 that gave me the error screen from time to time. The XBOX would start to read it fine though once it warmed up.
As for XBOX vs PS2 the XBOX wins hands down for graphics, controllers, XBOX Live and - most importantly - for the fact that you can mod your XBOX with XBOX Media Centre. XBMC is amazing and I don't know how I lived without it. I just have to get my wireless setup working again so I don't have the LAN cable running across the floor from my computer to the XBOX. It's so nice to not have to burn media on to DVDs.