I'll decline to recommend one over the other. I've had a Wisemic RX 200 which I used almost exclusively for a year before the 510 connector became wonky (common issue). I wasn't very pleased with its battery life despite it being a 3-battery mod. I was using high quality 18650 batteries (LG HG2 3000mah 20a and Samsung 30Q 3000mah 15a batteries)
vaping at 30 - 40 watts, and only getting a little over a days use with them.
Next purchased a Segelei Fuschai 213 Plus 2-battery mod. Again, using the same batteries and same mod settings, I only got a days use.
Next purchased a JAC Vapour series B DNA75W single battery mod. Using the same battery and same settings, I get a full days use. I attribute the better battery efficiency to the Evolv DNA chip set. The JAC is also much more pocket friendly.
One other consideration: How easily available are the 20700 batteries compared to 18650's? Since LG, Samsung, and Sony don't make 20700 batteries, your choices for 20700 batteriesare limited to Chinese manufacturers and I'm not really convinced they can make quality batteries comparable to the Koreans or Japanese.