We have all seen enough battery mishaps in the news, all from improper use in one form or another, improper charger, improper stacking, improper resistance load, etc.,etc. (key word in "improper")
So take the time to learn how to use whatever battery you choose to use safely. They all have their limits.
Folks keep saying to use AW IMR batteries, well there's a hell of a difference between a 1600mah 18650, and a 2000mah 18650 AW IMR battery, and you had better know what those differences are.
Knowing things like the Efest Purple ratings are the pulse ratings, and not the continuis ratings is kinda important in my book. Pointing out that knowing what the complete data sheets say may be quite different than what gets posted on a battery makers web site.
The key factors that I look at are:
#1 what happens IF something goes wrong? This is why most of us agree that only LiMn chemestry batteries should be used. They will still vent, but no explosions or fire.
#2 how will I be using the battery, and how much safety margine would be prudent? This means that sometimes the largest battery isn't the best choice. The larger the battery, the more energy there is to vent if there is a problem.
#3 how long will the charge last at my vape pace?
When I lay all of these factors out, the AW IMR 18490 1100mAh (16 amp) battery fits my needs best. However another persons needs can make that battery a wrong choice.