I've used USA transfers. Pro tip when you exit the airport and someone asks who you are looking for, they're actually there to help. All their friends work there and they are just trying to move things along.
I go to Playa a couple times a year. If you are you going SCUBA diving and need a divemaster in Playa for it, I can give you a connection, and he'll generally just come pick you up at the airport even - for a price (reasonable). Not sure what your travel plans include though. Otherwise, I can give you a small mom & pop I've used, for around $75.