Because you can oc the CPU multiplier independently, RAM is not quite an issue as it was in the past.
When you OC moderately, you will usually just keep your Clock at a flat 100 (and running the RAM at it's rated XMP profile).
And then achieve your overclock pretty much just by increasing CPU multiplier.
Don't overpay to get exotic ram, but do get the best RAM that costs about the same price, or with minimal added cost.
Usually this is 1600 and CAS9-9-9-24 as recommended above.
If you have no preference in colors, the other things to check are:
-can use one of the certified RAM models as listed by your mobo
-make sure it fits with your cooler