Do you mean ReBuildable Atomizer?
A dual coil RBA isn't the easiest to learn on...and one meant for a single coil, can easily be used for dual coils..all you need is a drill.
I always suggest the AGI...it is a genesis/
tank style that screws off into a dripper, so you can see which direction you'd rather go in. $10 on 101vape, but the easiest genesis to learn on is the RSST... drippers...they're all really the same.. I suggest an IGO if you only want a dripper.
If you want a tank for the best flavor, I suggest a kayfun clone.