I generally don't like to make declarative statements about intelligence especially on polls or opinionated topics that ask for people to answer questions based on differing criterias. Having said that; If Bob Sanders, and Nate Kaeding aren't in your top four, I can only come to one of the following conclusions:
1. You're devoid of mental acuity
2.You didn't watch much football in the ferentz era or
number C. You have a strange notion of things
Nate Kaeding was the best kicker in the Big Ten for three seasons. He was the best player at his position in the country for two. Best player at his position in the country for TWO YEARS! TWO YEARS! Did I mention TWO YEARS?
Bob Sanders was the heart and soul of our football team for three years. He single handedly changed games as both a run stuffer but also as a guy who would often take the best receiver for certain teams, and destroy them all day on the line of scrimmage. One of my favorite memories of Iowa football is watching the game against MSU in which Sanders used and abused Charles Rogers (pretty sure it was Rogers my brain is fuzzy) for an entire game basically. Jammed him at the line of scrimmage even though he was a safety, most of the game, and just completely dominated him, pummeling him into the ground repeatedly on jams.
The other two spots I think are legitimately up for debate. I can't imagine those two not on someones list. I also voted for Clark and Mitch King. My criteria on King was the amount of snaps he played for us, being undersized, and basically being the perfect picture of what an Iowa Hawkeye football player has been in the Ferentz era (high motor, over-achieving, out of position according to most, high effort, high character guy).