We were going to use ME, but last moment we found an awesome deal on a rental car, so went with that.
having only flown in to MCO twice now, with the first time taking a bus and the second time getting a car, I definitly reccommend the car.
When we took the bus it wasn't the ME, but it was run by the same company. We checked in for the bus, and waited an hour for it to come; not a lot of fun with a 2 year old. Then the bus was absolutly cramped, it took another hour to get to the hotel, then I waited forever to get checked in (possibly due more to it being friday then the bus).
This past time, We walked to our car, packed it (took maybe 10 minutes to figure out where our car was) and was off. The drive to WDW was a nice one, lots of stuff to look at. We got to our hotel (where I warned my wife about the long check in lines, and sent them off to look around) and there was no lines, no waiting. Checking in took about 5 minutes, and that was that.
Plus, driving to the parks instead of taking the busses is a godsend: you don't have to wait to get there, AND you don't have to wait to get back. We would get to the parks early enough and be able to walk to the front gates without too much trouble.