Familiarize yourself with manufacturers and don't buy anything with the word "fire" in the name, those are always the cheapest rewraps. My favorite batteries are Samsung or panasonic.
Panasonic is king and makes batteries for most medical devices so they make most sizes and they make them well. An authentic Panasonic wrap is very plain, the text/numbers are printed using a series of dots.
Panasonic makes a 14500 so google for that specifically.
Samsung 25R is my favorite 18650 incase anyone is wondering.
When shopping the higher mAh usually manufactured for longevity, whereas the tradeoff for lower mAh cells are typically for applications of higher amperage meaning intensity. Battery life vs power basically.