I returned from a 3 day rental with Payless, supposedly one of the worst. Pickup was a hassle, as it wasn't in the terminal like most of the other agencies. I did get an upsell (and got the prepaid fuel, which I was going to use anyway) and offer to upgrade. The location was a mess with just one person working, many angry customers (some trying to get a receipt upon return, others trying to get a car to leave with), but realistically it was less than an hour to get my car. And I ended up getting a Fusion Hybrid when I rented a mid-sized, and paid $100 after the prepaid fuel for a 3 day rental from Minnesota to Colorado.

So I think it is definitely worth considering these companies, knowing that you will spend a little more time picking up and may have a bit of an upsell.