I haven't been to DFW or IAH but I haven't found PHX so bad. It's not any longer to the new facility than it used to be to Avis or Hertz, and the wait for the bus is much shorter, since you take the 1st one that comes along rather than waiting for your personal rental car company shuttle.
The biggest problem with PHX is the unusually high fees and taxes. Total cost is usually almost double the basic rate.