I am retired, so all of my rentals are for leisure travel, not business. I've been pretty happy with Budget, but I'm sure a lot depends on the particular location from which you rent.

In addition to earning 1,000 AA miles (as an AAdvantage Gold member) on even a one-day rental originating at a Budget airport location, as a FastBreak member I participate in the Budget Bucks promotion, which gives me a $25-off coupon for every two rentals of two days or more. While that $25-off coupon is not combinable with other coupons, I find it very useful for one-day rentals, when there are usually no other coupons that can be applied.

(You can earn both Budget Bucks credits and frequent-flyer miles on the same airport-originating rental.)