I’d stick with Fenix, Nitecore, and Orbtronic for protected cells. Klarus and Olight have too many proprietary cells to avoid in 21700. For unprotected, everyone seems to like Samsung 40T (4 amp) for high drain and Samsung 50E (5 amp) for high capacity. They do last, but I think there are better options. I prefer Molicel P42A (4.2 amp, 45 amp high drain, and cold weather rated) or Molicel P45B (4.5 amp, 45 amp high drain, and cold weather rated); or Samsung 50S (5 amp, 25 amp high drain). Remember if you buy protected cells, you are paying extra for safety and insurance against ruining your batteries. Go cheap on protected cells and the protection might not even work.