Now that I finally HAVE one, LOL, I am going to agree that an RBA or an RTDA is probably WAY easier than tanks. OMG, wicking it right is the real learning curve with tanks.
I recommend rayon. Keep in mind I recommend that wick to EVERYONE, honestly. It solved 100% of my leaking problems, although I'd have to say that probably some experience with cotton taught me something, too. But switching to rayon makes it so.much.easier. LOL.
It's just a thought. Rayon's cheap (can get from Sally's or Amazon it's called Cellucotton and make sure you get the 100% rayon version, they make a cotton one.
Rayon's pretty sweet for leaking, (to me) because it shrinks when wet (cotton expands) and it plays to my strengths-- a desire to overstuff any coil I see with as much material as possible. It also lasts longer, can withstand higher wattages with ease, and etc. You still gotta get the general principles of how to wick done right, but for me, Rayon solved ALL of my leaking problems. Tight in the coil, and then a fair amount of thinning and trimming the wicks. Unfortunately, "how to wick" also depends on your tank or RDA, so watching a few reviews on your tank or RDA can be useful, not so much for the reviewer's opinion, but many of them are pretty good at illustrating how to obtain a successful build and wick.
Whatever you start with, tank or RBA, cotton or rayon, good luck! My first coil took about 4-5 hours and utilizing the husband AND ECF cliffnotes. I've come a fair distance from that point. THANK GOD. LOL.
Anna