Your question was, “Which external storage devices are dependable?”. The answer is, “none”.
The only safe backup is redundancy, meaning you have multiple copies.
I have have had fantastic customer service with Western Digital. Unfortunately, the only reason I know that, is that I have had at least four WD drives fail on me. (some explicably, such as an impact, others for no apparent reason) For me, however, since my drives are part of a redundant backup system, (NOW!) RMA service is to me more important than the actual reliability of the drive. Losing one drive out of three is no big deal if it costs me nothing.
