My top choice would be Dana Holgorsen.
Four reasons--in order--I really like Holgorsen for Iowa:
1. He's an innovative, offense-first coach, and Iowa has seen the best days in program history (in the '20's, '50's, '80's, and '00's) when they have been among the nation's best offenses.
2. He has experience recruiting from power states like Texas and Florida to a non-power state like West Virginia. I think that would translate well to recruiting players from Texas, Florida, and Ohio to Iowa.
3. He has significant ties to the state of Texas, both as a coach himself and in his coaching "ancestors" (Hal Mumme, Mike Leach, and others).
4. He grew up in Iowa.
Second this. Imagine his offense with a strong Iowa defense and great play on both lines. Would be sweet