Here are my fuel preference rankings. I use only regular unleaded, where available. No ethanol!
2. Kum & Go
(they are headquartered in my metro area, but have locations all over the US)
3. Hy-Vee Gas
(preference is given if I have a Fuel Saver discount)
5. Shell (none nearby)
6. KwikStar/KwikTrip (when traveling in NE Iowa/Great Lakes region)
7. Everything else is the same to me.
Now it's gotten to be that QuikTrip and Kum & Go are a tossup. QuikTrip was my no-exceptions go-to convenience store and filling station but now Kum & Go has improved in so many ways that they are extremely competitive with each other. I recently moved to a different part of town, and now QuikTrip is more convenient for me on my way home from work so that's what I usually choose.