I work as a Network System's Tech., so I've seen many a HD's go, from each mfr. I myself service about 300 systems (desktops, laptops, servers) from numerous mfrs and dates(HP/Compaq, Dell, GateWay, Aopen/Generics). Most of my experience has been with IDE drives from WD (Caviar), Maxtor (?), & Quantum (Fireball) for desktops.
I'd have to say that for a long time WD was hands-down better choice in performance, reliability, warranty, RMA procedure/support, Web download/Fact sheets (White Papers)/Controller Firmware/updates, and Diaganostic Tools (Data LifeGuard).
Maxtor has come a long way though, (I believe at one time their warranties were only 2 years compared with WD's 3 year). I had purchased a Maxtor a few years back because of an unbelievable sale, and I'd have to say I was happy with the drive, and never had problems. Plus they have improved their tools, drivers, & support.
To me Quantum (especially) and Maxtor drives were noisier than WD. Most of the Quantums honestly sounded like they were about to go right out of the box. A bit scary hearing that empty spray-paint-can sound. They did alright, but in the long run with a lot of re-ghosting (re-imaging) the drives, sometimes 4 times a year; Western Digitals seemed to have the best results and the least amount of returns. Now my observations could be unfair, because perhaps the WD models were of a higher grade than the other mfr's models we picked up. I can't be sure.
If I have the choice, I go WD. Especially for servers. Though I'll have to double check the RAID drives used in my HP/Compaq servers. Haven't had any problems with them.