For cotton, to avoid dryhits, I wick tighter than the usual youtube reviewers and fluff/thin tails and keep them short as possible. The cotton should in theory choke the coil, but it doesn't and dryhits-avoidance/TC-stability is much better. I once saw an old youtube review doing this for max-vg at high wattage on the older RTAs several years ago and the idea was that even though cotton swells when wet, then the high heat actually makes it shrink. I don't know what the actual reasoning is, but just know that it works better and doesn't choke and actually works a bit similar to rayon, in that it can take higher heat and is more quiet in sound and last much longer. I also think this is why rayon lasts much longer, as there's much more material to breakdown as tighter built.
I like the engine nano, but currently use the dual-coil version more. Dual-coil to me gives more volume/body in the vapor inhaled, though not neccesarily more vapor.