I prefer Shell V-Power 93 and use it every 4th or 5th tank. It's usually 20 cents more per gallon though. I normally frequent the cheaper BP 93 and Exxon 93. I have no problem with Citgo, Marathon/Chevron, Sunoco, etc. I would probably frequent the Sunoco stations more often if I drove past them more frequently. About the only brand I will bypass is Speedway/Super America, but I do fillup there on ocassion. In order of preference if price were irrelevent, and it was convenient: Shell, Sunoco, Exxon, BP, Marathon/Chevron, and Sheetz.