Pure ethanol ( most people can't get it ) has an octane "rating" of 115 actually. E85 has an octane of 105.

Octane is actually used to BOOST octane. Only 5.75% is required to replace MTBE in any area that uses oxygenates.

Thus, the lowest octane will normally will have the least ethanol.
In the Mid-west, mid-grade has the most ( a full 10% ) and out here, and 87 and 89 octane are the same price.