HEDP: apologies in advance if I'm misreading this, but based on your questions, it feels to me like you're a complete newbie to this --which is great, good to have more converts. But Li Ion batteries aren't quite as straightforward as, say, alkalines. Buy a low-quality alkaline, worst case the runs out of juice really quickly, maybe there's a slightly higher chance it will leak in your equipment and ruin it. With a poor quality Li Ion, not only can you expect poor performance (in a potentially much more expensive cell, so far more money wasted), but mishandled, these can do catch fire or explode, and the energy stored in a 3000+ mAh 18650 cell is NO JOKE. Hopefully you've carefully read and understood the handling, charging, using tips in the battery forum (although if you'd done that, I suspect you'd already have a good idea of what the good cells are).
Most of us buy higher quality brands, and stay away from xxxFire brands, because the higher quality brands have high quality cells (sourced from a few high quality manufacturers, such as Samsung) in them. And, we think (but don't know for sure) the safety mechanisms might be higher quality, too. Some high quality brands include AW, Eagletac, Nitecore, Orbtronics, etc. If a brand has "fire" in its name, I assume it's junk, unless someone on the forums tests and dissects it, and proves it's not, and I absolutely won't buy them. We couple these with a high quality charger that's been tested to use the right charging algorithm, including full cutoff at charge termination. Again, if you read the battery forum, you'll see the brands.
I have NO worries running good quality 18650s in quality lights and quality chargers. Rant over!
