ok. here's the main things you need to know about the companies:
gigabyte and zotac - max cooling and performance (while overclocked), with the sacrafice of noise.
asus - silence, not the best overclockability.
msi - the best of two worlds. its really reall quite, even under 100% load, and overclocks like a champ. I have a GTX 970 from MSI, and its super quiet, and I could overclock it a ton.
also, most of the companies make their same models of the 960, but with 4GB of RAM, if you're interested.
just make sure when buying cards, to get the real cards from the comapies, not the budget ones. the gigabyte one is called the G1 gaming gtx 960, the zotac one is the GTX 960 AMP! edition, the Asus one is the Asus Strix GTX 960, and the MSI one is the GTX 960 Gaming 2G (or 4G)