Unless random write speeds are high on your priority list, Seagate's three-year warranty is more compelling than Western Digital's two when it comes to external drives.
Western Digital's My Passport Essential is a pretty standard external USB 3.0 drive, which comes with a substandard two-year warranty. Compare this to Seagate's three-year warranty, and the maxim that all hard drives fail equally, then the Essential has quite a hill to climb at the start.
Western Digital has bundled the drive with SmartWare, its backup software that can sync files across hard drives to make things easier, and categorises them into sections like movies, pictures, documents and music. You can also set a password on your drive for security, which should work on both Windows and OS X.
We had two drives to test — a 500GB, which sells for around AU$79, and a 1TB drive that goes for around AU$119.
It's clear that assuming the same rotational speed, the bigger your capacity, the better sequential speeds the drive is capable of attaining. What's more interesting is that Western Digital appears to have done something magical with random writes, somehow bucking years of trends of reads being the dominant force.
Ultimately, external drives are much of a muchness, as we tend to treat them as devices that fail equally — with that in mind, Seagate's three-year warranty over Western Digital's two makes more sense to us. If you can think of an application where random write speeds are more important to you, though, and can't afford an SSD, perhaps the Essential line will pique your interest.