I've got a couple of box mods (
dna 30). Most of the time, I run 3.4V into a Russian 91% with a 1.5 ohm coil. The DNAs won't regulate at that low of a wattage equivalent. They're great if you want to throw on a dripper or put some serious heat on your
kayfun, but for the kind of
vaping I do most, they're not ideal. Plus battery changes are a pain, if you don't want to wait for a recharge via the USB port. You don't need a screwdriver to swap the battery in your ProVari. And the ProVari's build quality is much better.
If most of your time is spent with something other than a RDA, the ProVari may be a better choice.