Having talked to a couple of Lyft and Uber drivers riding to and from the airport it seems like Lyft is the better of the two. One of the drivers mentioned Lyft has higher qualification standards than Uber does for its "premium" service. He also said that driving as a premium driver got him a better class of passenger.
EDIT: One of my first rides was from a guy who drove a top-of-the-line Jeep Commander. He wore a suit, driving gloves, and a cap. Have to say it made me smile.