If you use it with 18350 batteries, you might be best with a 22mm tank that uses coils from 1.0-1.5ohms.
1.0ohm would give you a pleasant vape up to about 17 or 18 watts.
Kanger do the old 'mini' Subtank with SOCC 1.2ohm coils, but I'm not sure how mouth to lung you can get it.
Eleaf do tanks in the GS range also with 1.2ohm coils. I'll go and try the GS tank (22mm) at 4.0-4.2v and see how she vapes.