Hi and welcome to the forums!
I tend to like RED LED's best, but with that motherboard, it is hard to find a LED colour fan for that scheme. I have a Gigabyte X79-UP4 (purple/blue/grey mix), it's a weird colour also and I also have a Noctua NH-D14 (brown/light brown) as well as Trident0X 16GB ram (red)... it looks all over the place, but through the HAF X 942 window, it looks pretty good, and i have a huge 23CM RED LED fan (included) and it just looks awesome, Just get the fan that you prefer best. If you have a backlit keyboard that only is one colour, get a LED Fan that's the colour of the keyboard, that works really well. If your totally in doubt, go RED LED!