Stay the hell away from Apevia. Sure, it's cheap for an 680W, but the quality of those PSU's are pretty crummy.
The BFG's I really don't know anything about. The amps look good, but I haven't seen much else.
The X-Finity's seem to be okay since Ultra seems to have improved them over the X-Connects.
Of that list, I'd recommend the OCZ simply because of the proven units they've put out. OCZ doesn't make them, but they're essentially a Topower rebadged unit, much like what Tagan does. It's a safe bet.
You might want to consider adding Enermax and Antec 500W+ units to your list. Silverstone and Seasonic are a little pricier, but would be worth consideration. The Seasonic S12 line might be worth a look if you're picky about fan noise.
