I've had good experience with Amex roadside assistance. I needed a tow and a locksmith within a few days of each other. I called Amex, they got my address, and in both cases within about 30 minutes the tow truck or locksmith called me to let me know they were outside.
As an interesting side note, I struck up a conversation with the tow truck driver as he was taking me to the mechanic and asked him about how he got called. He told me that credit card companies or AAA contract with various 3rd parties to manage roadside assistant things, then those 3rd parties contract with smaller local 3rd parties who have direct relationships with the tow truck companies. Here's the chain: Me>Amex>Larger 3rd party>Smaller 3rd party>Local tow company>Individual drivers. It's amazing that there can be any profit in there for anyone, and it's amazing that it only took 30 minutes.