I live in the DC area. So about a month back, my parents were visiting. we went to a restaurant that was not terribly near to either our home or their hotel. As the weekend metro was being the weekend metro, we decided to cab back to our respective locations. I called an Uber for them since I figured it would be easiest. Since you can only dispatch one Uber per account, me and my wife had to take a cab. Looking at the difference between those two rides is why I stopped taking cabs.
My parents uber arrived promptly, it was clean and comfortable. It took them to their destination quickly, and the pricing was transparent and conveniently billed to my card.
When my wife and I finally hailed a cab, it was dirty, and the air conditioning was broken (It was about 90 F) The front seat had been pushed back as far as possible, and was in fact kind of bowed. The driver attempted to take some odd circuitous route back to our home until I asked him to take a more direct route. When we got there he tried to get us to pay cash.
This was an extreme example, but it made me think of all the other negative experiences I'd had with cabs in the city, they have been on the whole uncomfortable, inconsistent, dirty, poorly maintained, and discourteous (including drivers that pulled away as soon as they heard where I was going). At that point I realized that Uber was a better option. The worst Uber experience I've had so far was one that smelled slightly strange. For my area, it really is no contest, Uber is just better than the cabs.
Quantity is no substitute for quality, but its the only one we've got.