Western Digital. They are the quietest moving things in my case, fast, and have had none of a reasonable age quit on me.
Seagate is a good brand too, but I hate that all out of the box brand new hard drives from them I have dealt with are loud for being so new... Maybe after a couple years of use I could live with the loudness, but not brand new hard drives... Haven't seen any newer Seagates die yet, but my brother had 1 in his old eMachines system 200GB SATA only 2 years old and it was slow as crap and really annoyingly loud... I'm guessing it may have been a bad one in the batch.
I have a Toshiba in my notebook that I've had 3 years. 4500RPM, so not really fast, but decent when new. Now it's pretty slow, so I just ordered a new Western Digital for it.
Brand new, the only brand I will buy is Western Digital.