How do you ensure that the gasoline that you purchase is the best quality?

When I ran pump gas I had heard BP93 was on of the most targeted by racers. I ran it for several years with zero issues. I didn’t price check I just pulled in and bought it from the same station every week. During that time I would grab 10 gallons and run it in the race car, generators, and quad. When I switched to alcohol my hardest conversion was getting my quad and generators used to running on the cheap stuff again.