I quickly moved away from these sort of devices, but out of the ones mentioned I would certainly use a Kayfun if I owned it. Probably the only RTA I'd ever use.
I'm a dripper all the way.
1.) Mechanical mod
2.) RDA
4.) 30 amp continuous draw IMR (MNKE, VTC4s)
5.) Twice-boiled organic cotton wicking
6.) .5Ω Twisted Coil
7.) Your favorite juice
Doesn't get any better than that, of course YMMV. But in all honesty it delivers the most reliable, heaviest hitting, cleanest tasting, and most satisfying vape I've had out of any devices I've ever used. Sure you trade off the ability to chain-vape without worrying about getting a dry or burnt hit, but manual dripping is a skill that's easily learned. Could always get a bottom feeder too if squonking floats your boat but I like the accuracy I get from dripping by hand.
I am NOT recommending you sub-ohm vape, but as myself and many others know, these setups are top-quality in terms of performance and vape quality.
Check it out