100% gas is what works for me.
Here's the story. Ethanol contains about 80,000 btu's of energy. Gasoline contains 118,000 btu's of energy. Contrary to popular belief, higher octane does not equate to more power or more energy contained in a gallon of gas. Octane inhibits gasolines ability to burn. Higher octane gas is better suited for higher compression engines prone to detonation.
Since ethanol contains less energy per gallon, you have to add more gas to do the same amount of work. Bottom line, if you burn gas with no ethanol, you will see 5-8% better fuel economy (less gas burned to do the same amount of work) and about a 3-5% increase in horsepower. Yes, gas with ethanol is usually cheaper in most parts of the country. This is because ethanol is subsidised by the government and costs less per gallon. This encourages stations to purchase it because they can sell their gas for less. In some states and locals, it is mandated, usually at 10%. Use gas without ethanol and you will feel the difference and get better gas mileage. If you put a pencil to it, you will get enough of an increase in fuel economy to pay the difference in the cost.