I vote Western Digital. I have 6 Western Digitals spread throughout my systems. 2 x 400 Gig Caviar RE2 drives RAID 0 and a 40 gig in my PC. I have a 250 Gig in my Xbox. An 80 Gig in my G4, and an old 8 gig drive that I use as a semi-portable drive with a USB adapter. I also have 3 Seagates. 160, 40, and 10 gig drives. The 160 was DOA, and when I RMA'd it, the cheapskates gave me a factory reconditioned drive. That is totally stupid considering it did not ever function for me. I haven't had any problems with the Western Digitals, and thats all I will buy now.
But I would buy whatever you think is good. I think most people are somewhat biased when it comes to hard drives. I love WD and dislike Seagate just because all my WD drives have never had problems and got a DOA Seagate, and some people love Seagate because they haven't ever had problems, but dislike WD because one of their drives went bad. It's all experience with the brands.