I went with type of outputs/connections. Clearly I will need something that will mate with my system. Price if I need it, is not a major concern (within reason) Colors makes no difference because I could always paint it, or hide it.
Size would be a concern (honestly I would want something that is thin but wide) Kinda like rack size, so it can be placed in the HT rack.
Also a IR remote is a plus... Also like first poster said, no added distortion..
EDIT:: The reason I say yes to IR remote is because most HT will have a HT learning remote...