I think to some degree you get what you pay for. Sure the bottom-basement places nickel and dime you -- the advertised car price is like a loss-leader for them.
I like Budget, Alamo, and National.
For Budget, I book online under my free loyalty account, tell the shuttle driver my code and he phones it in. When I get to the (separate) counter, they have the paperwork ready and I sign. No questions asked except to see my ID. The rates seem reasonable.
For Alamo, they have kiosks. Sure the kiosks ask the same dumb questions about fuel, etc., but you can get through them really quickly, and again with your free loyalty account it already knows your preferences. The rates are sometimes lower than Budget, sometimes more.
For National, they have the "emerald aisle" where you just pick any car parked in a certain area for the mid-sized rate. They usually have a good mix including vans and SUVs (although I never need one). They are a bit more pricey. Then you just drive the car to the gate, give them your ID, and you leave.
Maybe because I look like a business traveler they just give up trying to upsell me. At National, sometimes they just say "you don't need gas or GPS, right?" But I used to go to Advantage (a Hertz company) to save the $10/day and they were freaking relentless. So I think the "nicer" places give more heed to your user profile.
Edit:
In fact, a day rental can be almost cheaper than a cab if you have a corporate discount code. I paid $40+tax for a day rental at Avis, plus a $2 fill-up. That took me from San Francisco to Muir Woods and Mt. Tam and then to the airport all in one day. The cab ride alone would have cost $50 to get from Union Square to the SFO.
Oh yeah, I used to rent a car one-way from Union Station in DC to Dulles when I needed to fly. It was often like $15-20, whereas a cab or shuttle was $30-$50. And I had use of the car for a day if I needed groceries or whatever (I didn't have a car).