Since both cards are 280's the one with the higher clock speeds is going to give you slightly better performance.
I would say go for the cheapest card and manually overclock yourself.
If you really don't want to overclock yourself then go with the one with the highest default clock speeds.
I prefer the looks of the MSI. I also don't really like the noise of the windforce fans, that tone under load is just the wrong pitch, and grates on my nerves. The MSI is quieter, yet cools just as effectively.
Go with the cheapest R9 280 because you can always overclock it yourself.
I'm not really worried about price. Is one specifically better?
The cards have the same specs except for core clocks and effective memory speeds. The GIGABYTE GV-R928WF3OC-3GD is the better card out of the two when looking at the core clocks and effective memory speeds. But if price really isn't an issue then why not make the jump to a GTX 770 at 264.99? It's quite a bit better than the R9 280 and it's only $25 more.