Esso's 93 and Petro's Ultra 94 are track-day fuels only for me. They are too expensive for day-to-day (18 & 19 cpl above the street price) and both are ethanol blended fuels. Shell's V-power is 91 octane, but it has no ethanol in it.

My '09 STi's fuel requirement was 93 octane recommended, but could operate on 91.

You just want a extra margin of safety when you're pushing it hard at the track.