Your best option is to wait for the DX11 ATI cards to have better circulation. A 5850 currently goes for $300, sometimes more, whereas the MSRP is $260.
If you've had bad experiences with ATI, it's more than likely from the 3xxx series or earlier. I'ved owned or have experience with the following gpus:
As far as I'm concerned, ATI has given me no more trouble than my nvidia cards have, and at the end of the day, it's about price/performance, not red or green.