They're all made by sapphire (even the BBA ATI ones) so basically they are all the same. What youc an do is look if any brand uses a ATI Silencer 4 (wich totally owns) or compare their costumer support quality.
Considered as good are: Sapphire, Connect 3d, HIS (because they use ATI Silencers on some cards)
I would avoid Asus since they allways seem to screw something up. Their own cooling solution on the XT PE totally sucks for example.(Cooler is over the memory chips but not cooling them, even heating them up more!!!)