This is not as easy to answer as simply saying this is the best brand and model, Unfortunately. 18650 batteries come in a variety of chemistries and some offer protection circuits while others do not. I think this is important enough to not just state, but to do so while making extra effort to make a point. I will highly recommend you study up some. Everyone here will recommend that if you are new, opt for protected cells. These cells sacrifice a tiny bit of capacity to store a chip that prevents overcharge/discharge and heat protection which prevents the cell from possibly shorting out or worse, exploding. Avoid at at costs bootleg cells (especially anything with FIRE In the name…)
There is a ton of info with testing results here:
-------------- Mooch’s battery blog
-------------- Mooch's blog | E-Cigarette Forum
Here are some more resources:
EVERYTHING YOU NEED TO KNOW
protections
chemistry comparisons
battery guide (i actually get my batts from here)