is your actual question more like, "is there a resort where the bus rides will be shorter because it is closer to everything?" If you only plan on going to one park, choice of resort based on location works. if you plan on going to more than one park... the law of averages takes over. The differance between the resort with the slowest bus service and the fastest bus server is plus or minus 8 min. over the course of a 6 day trip.
That means, if you plan on going to all the parks figure your travel time will be about 40 min. (including wait time at the bus stop).