XFX value is in the warranty, MSI would be in the cooling solution and overclock ability and so on. The only ones I would not buy is the powercolor.
Most of the time you get a better and quieter cooling solution with the overclocked cards but it is user specific if it is worth the extra money.
Usually the powercolor brand is a budget brand but the prices you posted are not much cheaper than the others. Their cooling solution look and feel more cheaply made and therefore should be noticeable cheaper than the other brands.
I have had 2 Powercolor cards before and they worked fine but both where bought because there was noticeable savings over other brands.