I like Zoey's in Marion a lot. Great Plains was always good when I ate there, the Buffalo on wheat was my fav. Mabe's in Decorah is very good if you like thin pizza. PollyEyes (sp) in Iowa City is very good. There is a really good place in Fairfield, but I can't remember the name.
Surprised by the number of people that like Happy Joe's, as I always thought it was Chucky Cheese without the annoying mouse. May have to give it a try again. Casey's does a pretty good job for being a gas station. If you live near a Sam's club, you can call in and pick up a huge pizza for about $10, but your choices are limited. Their supreme is pretty good, as is the all meat.
One place that use to have horrible pizza but has really stepped up their game is Pizza Ranch. Still not close to the best, but much better than it was.