I am a computer Technician, seeing bad hard drives every day. and I can tell you for sure that seagate drives are much more reliable than WD drives. Maybe it has something to do with more PC Companies use WD drives? All I know is that 8 out of 10 dead/failing drive i run into are WD... When I test the drive and it fails I say to everyone "Watch this will be a WD" and sure enough usually always is!
Not to mention, on a drive that I purchased 2 TB WD External (black friday deal 3 years ago for $80 bux, a deal too good to pass up! Still considered a good deal even 3 years later!) but that drive died about 10 months after purchase, luckily i was under warranty they sent me a brand new 2TB drive (updated model with USB 3.0 support). and so far no issues (knock on wood). except for the fact that i only have 100 gb left lol.
But if i were looking for reliability i would go with the Seagate, and the 5 yr warranty is an added bonus!
now dont get me wrong , i have seen seagates fail many times. just not nearly as much as WD Drives. even 15 years ago when i got my Packard Bell (133mhz pentium, with a 2 GB Seagate) worked beautifully for a few years, but then i wanted to upgrade. so i bought the biggest drive on the market a WD 8.4 GB for over $200!!! (i believe in '98). but even then that 8.4 didnt last very long, i wound up putting the 2gb back in the Packard Bell and it is still in there. Its in storage, obviously not used anymore.