The vast majority of the time, I do the same thing almost all consumers do which is buy the cheapest gas they can find. 90% of consumers don't give a shit about ethanol, they only see that it's cheap so that's what they use. Personally, when driving in the city I see less than a 1MPG difference so paying the premium for pure gas just isn't worth it.
Also, just to clear up the misconceptions about how much Iowans care about farming: 60% of Iowans live in urban areas, only 25% of Iowans have ever farmed anything at any point in their life, and only about 17% are currently employed directly or indirectly in agriculture. The vast majority of Iowans do not give a shit about farming or ethanol.