My list from the last time:
http://cyclonefanatic.com/forum/off-topic/174119-best-favorite-iowa-beer.html#post3545963
I'll stick with my pick. Psuedo Sue is far and away the leading beer coming out of the state in terms of universal nationwide praise, and that's not a slam on any other beers - Psuedo Sue is considered by many to be one of the best beers in America right now. I beer trade with guys in California, Pennsylvania, and Connecticut, and they prefer it to Pliny in overall quality. Their words, not mine. It also has an overwhelmingly positive response on Beer Advocate:
PseudoSue | Toppling Goliath Brewing Company | Decorah, IA | BeerAdvocate
Confluence is very consistent, and they put out a nice, wide variety of good beers. There isn't a single beer that just blows me away there, but they are universally well above average for their style.
515 is up to some wild stuff. I've only had them once, but really liked it.
Those are my Top 3 breweries in the state, in order. Does Peace Tree still make Hop Sutra? That's a great DIPA.