Best AMD GPU manufacturer?

I have an MSI card and love it. XFX is an even better company and I have heard pretty good things about Gigabyte and Asus.

XFX cards have awesome support so I would say XFX  . Quality is about the same with all of the brands, so I look at service and XFX trumps all but EVGA (who makes NVIDIA cards) in my opinion.

Asus, Sapphire, Msi, Gigabyte, XFX, and HIS are usually the top 6 chosen suppliers for AMD cards. for the 7850, they are all pretty similar due to the fact that the 7850 is efficient on its own already. the best one will probably be the cheaper one of the bunch(which at the moment is the MSI Twin Frozr model on newegg)

To be honest, most of them will be the same. I wouldn't say that any one manufacturer is better than another. As dudewitbow said, the 7850, as with the rest of the 7xxx series cards, is good enough that the different coolers won't really make a ton of difference. XFX is the only board partner that AMD has at the moment that offers their cards with a lifetime warranty though.

Most manufacture had PCB build by third parties (factory in china usually), so sometimes even different brand they were build by same factory with same quality.......

The thing that differs is, how good the cooler, price and after sales services.......