I've used Discount Cab probably 10 times in the last year living in Tempe. All of my experiences were wonderful, aside from two.
One time I got a driver who was training with a supervisor of some kind and he was doing a terrible job. And he was unsafe on the road. However I think the supervisor in the car knew this while it was going on. Another time my driver was just plain rude and insisted that he knew my destination- and continued to drive in the wrong direction when I was telling him exactly where to go.... driving up my tab.
However I can 100% say that 10/10 times the cab has been here to pick me up within 10 minutes or less. Today I had a cab in 4 minutes...! 8/10 times my driver has been super friendly and talkative. I only use this company.. I never use Uber or any other taxi service because I generally have a great experience with Discount Cab. I trust them over the other services that I don't know.
Today I actually left my keys in my cab. I called the company back- and my driver called me within 10 minutes to let me know that he talked to his boss and he was going back to my apartment complex to leave them in the office. I don't know if it gets any friendlier than this!