We used Transtar Towncar service this past September for the trip from MCO to WL and back. They were great. Driver was waiting for us in the baggage claim when we arrived. He was very friendly, well informed about the Disney schedule for that particular week (park/show times/rides under rehab, etc.) was familiar with our resort and helped with the bags.
Car was comfortable/spotless.
On the return trip they actually sent a complimentary stretch limo (I think usually happens when it works better for the company to schedule that way). Which made the always sad ride to the airport a little more comfortable.
Even without the limo though, great service all around. We'd use them again without hesitation.