I use whatever is cheapest.
when ultimate first appeared i tried it out, noticed ?5 more on filling, and 10% decrease in economy with no noticable power difference...not impressed.
These days i use whatever i can get cheapest which used to be supermarket but on my commute these days i detour to Trago mills where i can get Shell fuel currently cheaper than anyone else.
fuel is fuel, it all meets the same standards!