How do you pick a healthy betta fish to buy?

there is not really a "best" betta to have i do not recommended dumbo bettas also known as elephant ear bettas because it it hard for these fish to swim and is not a good life for them never under any circumstances keep males together some males will get along with females if you decide to keep males and females try to get a young male he will get used t them i will probably not fight if they do put the male in a jar put a hole in the lid for air and put him back in the tank of females a few days later. females don't fight. i have breed bettas so i know a good bit about them:)