From the benchmarks I'm looking at the 5850 is actually a little faster (at stock speeds). I run with the 6850 and it's a great card but look at a new 7770 since it's in the same price range. The 7770 Vapor-X is a really good overclocker, current generation and is cheaper than a new 6850.
Also the 5850, being 2 gens older, won't get any better with drivers. The same goes for the 6850. The newest drivers from AMD (12.11) actually gave a 5% increase to the 7770. So if anything the 7770 has a chance to actually increase performance where as the other two are stuck where they're at.
I just typed in on ebay "7770" and there was one timing out in less than a minute, i quickly checked to see it was all good and bid on it, won it, a Gigabyte 7770 for £87 total, good deal or am I an idiot
I just checked the new 12.11 driver release and i'm feeling pretty confident I made the right decision in getting a low end 7770. I also have a 550w psu so the less power consumed the better.
Those are using extremely old drivers. Anandtech doesn't update it's benchmarks when new drivers are released. Those benchmarks are from the release of the 7770. The 7xxx cards have seen two driver versions that have increased performance and reliability. And as I said, the 7xxx cards should continue to get better until Q1 2013 when the 8xxx (or whatever they're going to be called) release.
Lol, I felt the 7770 was over priced, so I canceled my purchase and bought a 6850 for £82, however its quite old and the same asus card but newer with everything in it ends soon and i'm going to try and get that for a similar price and cancel the old one.