so many, i don't even wanna know...because i don't use the vast majority of them. after trying a few cig-sized junky ones, i bought several of every joye 510 size (and pcc's and passthroughs) and every contraption to go along with. i then moved on to ego-t's and ego-t passthroughs -- the passthroughs were irritating (cord is too short, and the charging can't keep up with my extreme chain-vaping), HATED the ego-t tanks, but LOVED the 1000mah batteries.
i then started collecting insane amounts of "ego-type" devices (echo's, etc.)...meh, ok, but not it. i then went back to my trusty ego-t 1000mah batteries, with boge LR cartos -- very satisfying, but hated having to constantly top them off...so, i then tried virtually every popular gigantic contraption as a substitute...a few were semi-decent (such as the EMDCC), and all the rest were complete junk (constant fiddling, burning, failure, DOA, etc).
so, i went back to the boge LR's and constant refilling, swearing i'd never buy a DCT -- i lied. after reading umpteen favorable reviews on ECF, i caved...sure glad i did. i'm now in vape heaven with my (currently) "perfect" setup: *single* coil 1.7 and 2.0 cartos in 3.5ml chrome DCT's (along with aluminum drip tips) atop my ego-t 1000mah batts...no muss, no fuss, reliable, long-lasting, and everything is easily and painlessly ($) replaceable...speaking of which, i've never gotten into mods (thankfully), as i tend to misplace my pv's A LOT (in which, of course, i inevitably find each time, right after i buy a new one, argh).