I was recently shopping around for a couple of external hard drives. I ultimately came down to a decision between the Seagate Backup Plus and Western Digital My Passport. I ended up buying both so I could compare them for future reference.
The Seagate has faster reads, and the Western Digital has faster writes. Overall performance is hands-down the Western Digital drive, but be warned it is a heavy brick compared to the style of the Seagate. The following benchmarks were performed on Ubuntu Linux 15.04 with the gnome-disks utility, straight out of the boxes.