I totally agree. In most cases the mod will outlast the battery. Waiting for a device to recharge is the worst, especially if the battery doesn't last a full day. I usually buy my batteries from VE cause I know they're a legit source, and I get some reward points that add up. Also they seem to be as cheap or cheaper than ebay. Can buy by the single, and pick up some wraps and a case from the same location too. Not to mention shipping is free as well over 50. My regulated favourite 18650 is Sony VTC6 My unregulated favourite 18650 is Sony VTC5a For 20700 I prefer the Efest since they're easy to get and no messing around with the number of positive posts like the ijoys.