i have a couple of external hdd that im using.

1tb Western Digital My Book Essential
1.5tb Seagate FreeAgent Desk
500gb wd passport elite
500gb wd passport (for my wii)
160gb wd passport

to be honest, they all work ok. i'm not brand loyal, i just look for the hdd that 's the best deal
for some strange reason the best deals i can find for externals are western digital and the best deal i can find on internals are seagate. can't complain, none of my hard drives from the past 3 years have failed on me.