Well, as far as brands go, I personally run a couple Platinum LED's, and have liked the results with them. Tasty LED makes some really nice rigs that are running some nice effieicent COB's (so get a nice, full spectrum white light and not the pink/purple light). I can't remember the site or company, but I think
@BigSm0 may know that's making a really nice single COB light. Think they're called AutoCOB or something like that.
Couple to check out.