SJC is more annoying than SFO because it used to be so great. Like CLE, SJC charges $5.00 for the ride. Avis has an off site rental spot on North First Street. Hertz has one at the Hyatt.
LAX has one of the better large airport shuttle systems. And at most CA locations, you're not paying the high extortion fees charged by so many airports. 8.25% sales tax is the only add-on at LAX.
Yes, walking to the rental site that has expedited service and no heavy taxes would be the ideal airport. Does OAK still work that way?