XFX, with their double lifetime warranty, is the easy choice for ATI based video cards. They also make the fastest single slot video card out there (5770). Can't figure out why they're the only ones to achieve this.
So far enjoying my experience with XFX. Their respectable customer service helped smooth out some problems during the double lifetime transfer and definitely boosted my confidence in the company.
Actually I really like their customer service, has been great in my experience and while one hopes you never need it, let's face it high end components can break.