Hi Mark and welcome to ECF. My suggestion would be either the Kgo or the E-Power. both are true 3.7 volts and have batts that are approx. 1100 mah. 100 mah= 1 hr
vaping before recharge. Either kit costs about $40. Also has the manual batts which are good cuz:
less chance of damge from juice
some autos fire when loud sounds occur
best of all it puts you the vaper in complete control- if you want a stronger hit hold the button down longer.
These 2 PVs also allow a wider range of cartos and attys.
As for tanks you can always add on a tank (uses disposable cartos) later for about $10-$15. Or you could move up to a Clearomizer= tank and element in one
Diff between Kgo and E-Power is the batts- Kgo batts are $15+ whereas the E-Power batts are seperate from the unit and cost $5.
Good Luck.