I ended up renting from Enterprise but looking at how things are set up it seems like renting from National, Alamo, or Enterprise would be a very similar experience. All three counters are side by side, but the Enterprise one is separate. Both National and Alamo had short lines, and Enterprise did not so we were in and out quicker than if we had rented from the others.

On return, we were waved into a line where the guy was servicing all three. He just wanted to know who we had rented from. Otherwise, just like renting from National.

We didn't look too closely at the National selections, but from what I recollect there were mostly Altimas and Chrysler 200s. There was also one mid-sized SUV that might have been an Envoy. Interestingly, both Enterprise and National had primarily out of state registered vehicles. We counted around 20 before we saw on with Iowa plates.