I was thinking about the 21700, but, how long will it last... 26650 have been the rave also, but seems to be dying. Not trying to contradict, but get the best opinions. Keeping in mind I am a simple Mtl’r
Personal for me is a strong preference for 18650. I can't say it's the correct choice, but it is mine.
There is no wrong way to vape.
Unless you put it in your mouth .... end first. That won't work.