Looking to add a backup desktop hard drive

[Egnever]

6. Unless you store a lot of photos or videos

A handful of terabytes is useless.

Most people in my experience use less than 60 gigs of drive space.

Overbuying storage serves no purpose whatsoever. For that same $150 you could get three years of unlimited storage with a service like carbonite that is a much better backup anyway since it is off site and would protect you in the case of a burglary or fire or other natural disaster.

Given the average hard drive life is 3-4 years in the end you might save yourself a dollar or two going with an external but should a disaster hit your house all that extra storage would be for naught anyway.