My feeling is that you would be better off not having the ethanol. It attracts water and it's hard on rubber fuel components (lines, fuel pump diaphragm, carb needle/seat assembly, accelerator pump diaphragm, etc). Those parts will tend to wear out quicker.
If you drive it all the time, the water should not be much of an issue. I have '71 Cutlass that may only get refueled every other month. That gives time for water to accumulate and cause corrosion.
If it's no more than 10% you probably won't notice much difference. Going over that is uncharted territory and is the subject of current debate with the EPA, ethanol producers, and car manufacturers.
ethanol is cheaper if you're worried about saving 10 cents a gallon now but at the same time you'll be putting more gas in your car faster than you think because the mileage per gallon dramatically decreases.
both of the previous answers are correct, but if you live in a metropolitan area where you have emission tests it is probably a moot point since the EPA usually requires 10% in all fuels in those geographic areas.