I have a XFX DD HD7870. I've had no trouble with it. I don't hear it while playing games. Of the two you listed, I've owned MSI cards and they were also trouble-free. I have not owned any Gigabyte video cards.
The gigabyte core clock is 1100 mHz and only costs 230 so I'm probably going to get that one http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The three fan mechanism is kinda cool and I'm sure it is quiet but that's just one more fan to quit working on me, but if it's built well then I won't worry about it. I hear some companies use cheaper parts in their card to bring cost down and I wanna make sure I have a quality card all around that will last. I hear xfx tend to use cheaper parts for their card but I may be wrong
Sapphire is pretty cheap and it's so cold in my system. I had a 4870 before I got the 7870 and that used to run at like 68 Celsius idle (terrible i know) and with no other upgrades i have my 7870 running at 25 Celcius.