I'll buy anything that has a reliable OEM drive inside. I know PQI and MSI use Samsung drives, so they're good in a pinch. Toshiba din from CDR-King, that's what I currently use now. Western Digital has been a favorite of mine, with a balance of clean aesthetics and reliability. Basically, as long as the housing and ports aren't flimsy, you can go as cheap as you can.
If I'm using the HDD to store media exclusively, I'll pick the 2TB. If I'll be using it for both data and media, I'll take two 1TBs, and make my data redundant on both drives while splitting the media (e.g. movies in one drive and music in the other).