I trust the kanger bcc stuff more than anything else I've tried and found these:
Kanger E-Smart-C 808D Bottom Coil Clearomizer - EVcigarettes.com
This product is a pain the .... IMHO. Unlike the Joyetech Ecab which is also 350mah, it doesn't have changeable (loose) batteries, instead the eSmart has to go onto an ego charger...during which time you cannot use it.
My vote is for the Joyetech eRoll.....I clench it in my teeth all the time. Drawback is small tank size... 0.5ml but I fill up about 5-6 for the day, then wash at night, dry on windowsill, ready to fill again next day.
So what's the deal with the eroll replacement atomizer heads, they seem absurdly expensive and 2.2 ohms... isn't that a bit high of a resistance for 3.7?
See, all the "Kanger people" say stuff like that

I have 2 eroll atties going on 2 months now. I soak in hot water, then dry. There are a couple of GREAT YouTube videos on how to rebuild them.....the coils hardly ever go, it's the wicks.
2.2ohm is perfect for the eroll. It hits like a train for such a little thing.
low resistance coils 1) get too hot and 2) burn out quicker.