this is an easy one. It comes down to where in the world you are though. If you are state side then Orbtronic 3500mah 10amp protected button tops. If you are not state side then the Keeppower version of the same core cell Orbtronic uses(Sanyo NCR18650GA)which is also a protected button top cell. There are a couple new "3600mah" cells floating around. One is from Olight and I think the other is Klarus. Lots of members here have tried to find out what the core cell is on these supposed "3600mah" Olight and Klarus cells only to find zero information. Many here have the opinion that these "3600mah" Olight and Klarus cells are actually the old 3400mah Panasonic/Sanyo NCR18650B cells for their cores. The 3400mah cell can indeed have actual capacity approaching 3500mah so many of us here suspect Olight at least just rounded the capacity number waaay up and called it 3600mah. Avoid those. The last legitimate 3600mah protected button top cells used the no longer for retail sale 3600mah NCR18650G cells as their core cells. I jumped on them as soon as they went on sale and bought I think 16. But...still. Either Orbtronic or Keeppower 3500mah protected button tops are for now the best protected high capacity 18650's I know of.