For strictly airport to/from transfer service, you'd be crazy NOT to use super shuttle. I've used SS all over the country, a lot at Skyharbor and Mesa Gateway. I've always received instant confirmation of the booking, and if you actually check the box for text messages.... You won't receive a robo call informing you how far out your driver is! It's handy, affordable and never ever had a problem in 10+ years of using them.