Chevron is a good brand of gasoline. Buy from a busy station to ensure you get the freshest gasoline.
My (Porsche) tech buddies tell me they believe Shell V-Power provides more power, this via a butt dyno, than Chevron but all agreed with me when I reported how much better my N/A Boxster engine ran after a tank of Chevron Supreme after being fed a steady diet of Shell V-Power. The cleaning action of Techron is amazing. They said that while they run Shell V-Power most of the time occasionally they'll run a tank of Chevron for the benefit Techron provides.
My 996 Turbo could have cared less. It ran good on Shell V-Power and while it didn't run any better on Chevron it didn't run any worse. The cleaning action of Techron didn't make any difference. I suspect the Turbo engine is just a naturally cleaner running engine.
For both my HC and my Mini JCW (with a turbo-charger) mostly I run Shell V-Power. (My decision to run Shell is helped by the fact there is a Shell station in town that sells its gasoline at a slightly lower price than other stations around.) It is subtle but both engines seem to prefer Shell V-Power over Chevron Supreme. However, towards the time an oil change is coming due I switch over to Chevron the last tank of gas before time to change the oil. I just switched the JCW to Chevron as the car is just a couple of hundred miles away from its 5K mile oil/filter service.
I avoid supermarket/discount gasoline because these resellers live on the thinnest of margins so they buy the least expensive gasoline they can find. While the gasoline (probably) meets requirements its quality may be towards the lower end of the spectrum. Thus for consistency's sake I stick with buying gasoline from name brand stations. If one is observant he can find stations that sell gasoline at a lower price than others of the same or comparable brands. I have about 4 or 5 stations between my house and my work place -- a distance of about 30 miles -- that sell gasoline at very competitive prices and I use these when it is not convenient for me to make my way downtown and fill up at the Shell station I mentioned above.