heard good things about the istick 50,has 4400 mah so should last the average vaper like 2-3 dayz and the advanced 1-2 what i am using atm is the kanger KBOX,just simple and sturdy,works a treat its using 18650s though, a freshly charged one is lasting exactly a whole day for me (veritas @0.4ohm @20-25W)