Are those your only 3 choices? If not, let me also suggest the Cloupor Mini (30W), mini-plus (50W TC), and GT (80W TC). The 30W mini is identical to the Sigelei in size/function and runs less than $30. The 50W right now at 101Vape.com is $29 with coupon code Vapetober! Another good built-in-battery mod is the Wismec Presa... standard 40W version and the 40W TC version run from $27-49 depending on where you buy and which version. They're as well made as an Innokin MVP, too. I've not tried the Koopor yet, but it's getting good reviews, and is also a sub-$40 mod as well... (also uses 18650's). To me, charging batteries separately and keeping them handy for switch-out is what makes ultimate convenience... you're never without power, and never have to worry about finding your cord or being tethered to the cable while it charges! Yes, there's the added expense of batteries and charger, but $25 extra will buy a pair of quality batteries (from Jason's list above) and a good NiteCore charger