I had to RMA a Fujitsu drive a while back -- the manufacturer warranty on it was 2 years, and it failed after just over a year. The retailer's warranty was only a year, but they took the drive from me and sent it on to Fujitsu, anyway.

It took about 2 months for them to send me a replacement, which was a little long, but I didn't actually need the disk for anything. They also sent me a 30Gb disk to replace the 20Gb disk I'd sent them. Which was nice.

I've had very little bother with IBM disks, although there was a bit of a problem with the Deskstar 75GXP range a while back -- one of mine (a 30Gb) went crunch, but I've yet to actually RMA it.

Essentially, I'd choose IBM disks for most things, although I did buy a pair of 80Gb Seagate disks for my Linux box at home a couple of months ago.