At work we resell a lot of Dell GX-50 and 60 desktops. They have little low-profile Maxtor 20 gig hard drives in them, and we must have had at least 20 of them come back with dead hard drives in the last year (out of probably 50 or 60 that we've sold) :-o
Not surprisingly, Dell replaces them under warranty with mostly Western Digital or Seagate. Personally I've used WD, IBM, Maxtor, Seagate, and Fujitsu on Amigas and PC's, and only one has ever developed issues -- the WD 40 gig I got back from RMA after I sent the original in due to it being really noisy. Its replacement has recently developed some bad sectors.
The only other HD trouble I had was with my original 80 meg Segate that came in my 1200 when I got it used. I bought it with the understanding that the HD didn't work, but when I first turned it on, it booted right up :-D Once in a while though it wouldn't spin up and would need a little shake to get spinning.