RBA and RDA are different. I don't own an RBA, and haven't really looked into it, but I know I've read they're harder to work with for beginners. (I'm probably wrong, if so disregard)
My only RDA so far is an Atomic which has adjustable air flow. As the guy in the local vape shop was showing me all sorts of tanks, I quickly decided on the Atomic for this reason alone. Very easy to build.... and you can adjust the amount of air flow you get (small/medium/large holes, which can be let in from either 1 or 2 sides). VERY handy.