I would go with whichever one I would be least upset about losing or wreckingFor me, that would be whichever one costs the least to replace.
Yup, I'm going with the ego type battery and the kayfun mini clone. I got the mini clone from angle cigs for $20 +/- and the Battery's are cheap and I hardly use them anymore. I'd take the fast tech stainless nemesis clone but then there would be locking rings to mess with. It was only about $25. I only use it to fire my builds now. And as a base for building coils.
Thanks for the input.
That's what happened when I got the ProVari I wasn't going to use until most of my egos died.
Easy to then just drop it if I need both hands...

You get to open it whenever you want.