The majors here all seem to be about the same, though now and then a convenience chain location will have .10 less for regular.
Since April of '20, I've been gassing up on E0 87 octane at an small independent service station in the city. Right now it runs about .08 more per gallon than the average price at Exxon, Shell, etc. I imagine I get a small bump in gas mileage -- not enough to pay for the extra cost probably, but I'm supporting a local business. And I fancy it's better for the Buick's digestion.