I have found that Sunoco seems to have the best blends. I know at my local Sunoco, they have 10 cent Thursdays. They cut the price of Super Premium (93+) ten cents on Thursdays. That brings the cost back to about what you would pay for midgrade. I try to only fill on those days. Mobil also seems to be good, but is a bit pricey. I get roughly 13.5 in mixed driving with my 5.8 bronco.
Rich