Since I asked, it seems only right that I answer.
There's a Mobil station a block from my house I've been going to for a couple of decades on a regular basis. The next closest station was Exxon. Two blocks away, but the price was generally about 25 cents more per gallon, so why bother? Recently, it changed to Gulf and the prices matched my Mobil, but over on a VW forum I still visit, no one seems to like Gulf.
I posted this question mostly because I was curious to see if anyone is a Sunoco loyalist and if they bother to go with their 93 octane fuel.