I've parked at the AAA in Magic kingdom and it is a mixed blessing as there is no tram service there (as best as I could determine). Yes, it is closer to the T&TC but you have to walk there (you go under the bridge). It isn't too long a walk but it is not just across the street either. So if you want to really minimize walking, go with regular parking & the tram. If you don't mind about a 5-10 minute walk (and no waiting for a tram), go with AAA.