IBM drives started going south before they moved manufacturing to Hitachi. I've not seen any improvements since then (can't say they've gotten worse, but no better). I've yet to have a Seagate drive fail on me. I've not had any of my own WD drives go bad, but I have seen one die on a customer. WD was more then willing to work with me on getting the replacement drive fast (less than a week) and then send them back the dead/malfunctioning drive within a reasonable time frame. Maxtor now owns Quantum, which I've had the circuit boards pop on (litterly pop when the board blows a chip) essentially killing the drive (not worth the $2,000+ for data recovery).
I'd use either Seagate or Western Digital drives in a build with confidence. Of course, I won't use any drive that doesn't have at LEAST a 3 year warranty on it. Seagate's 5 year warranty is just another place they shine. Especially since that's across all their drives now, not just specific model numbers.