I can convey personal experience and preference. I have used Seagate, Maxtor, Hitachi, Toshiba and Western Digital Drives for various applications. I stick to Western Digital for reliability. I have not experienced sustained reliability with any of the others, although Maxtor comes close.
My personal philosophy with external drives is many smaller drives, vice fewer huge drives, because as we all know, electronics will eventually fail (usually right before the planned back-up that you were meaning to get to) I do mirror image the drives from time to time, in a manual RAID, if you will, disconnect, and place in safe storage as back-up for impending disaster recovery. This is time consuming, but not nearly as time consuming as recovering what was lost. I have suffered the loss of a 320GB drive, and the time spent to recreate the files, reconstruct what I already had is time that you will never get back, twice. In the long run, it is cost effective to me, to have a redundant back-up, because the music really is that important to me. Thank God for archive.org, saving my butt in the long run.
I think (and I have been recommended by many to stop doing this) that the MOST relaiable way to back it up securely is one of the many reliable online data back-up companies. They multi-RAID (sic) their servers, have insurance, etc. Experience here is that I can quickly and easily access my information at anytime, from anywhere, without lugging a drive around with me.