For unprotected 18650, I like Molicel M35A cells. 3500 mAh rated, 10 amp discharge, and rated down to -45 degrees C. Some brands don't live up to their ratings, or die prematurely when used at high outputs. Most don't hold up in cold weather. Don't get crappy cells that claim to be the best. Get cells with a proven track record showing they are the best.