I've heard that MSI is really good.
I shall say this though: if you buy an XFX, you will be disgusted. You WILL BE disgusted!
Leadtek, BFG, and MSI are all really good. I have a Gigabyte, and I like it, and it scored really well in tests, but it runs hot for me. So, basically, if I could go back with this knowledge, I'd get myself a BFG or MSI... Or Leadtek.
Personally, I've heard more good things about MSI's card than any others, then Leadtek, and then BFG. I know someone who had a BFG 6600 GT and it didn't perform well, and he had to send it back. He got a new one, though (still a BFG), and it worked fine for him. He still has it, too.