USA seems to be a frequent favorite, so we tried them again this year, after having a problem a few years back. Waited 25 minutes with their greeter, before being asked to walk with luggage to another terminal despite my wife's foot injury. When I complained, I was initially given 'dog ate my homework' like excuses, including heavier than normal arrivals in Cancun due to a hurricane in Cabo.
Next time we plan to use cancun-cab.com. We have never had a problem with them and they are usually a few dollars less costly. Canada Transfers and Cancun Valet are also well regarded.