Space. I have a two bay 3.5" case that isn't terrible, but 3.5" drives tend to be bigger, louder, and cost about the same for 2TB anyway.
Edit: Well, $80-$110 for 3.5" and $120 for the 2.5" (maybe I'll get lucky and see one for $100).
Edited 1 time(s). Last edit at 06/13/2014 06:52AM by silvarios.