Best defined as how? Easiest? Cheapest? Most reliable?
Easiest is just paying Disney to do it. No worries, but it can become expensive fora family of 4.
This is why others suggest a car hire service. A limo could be cheaper, and certainly more fun, and can include a stop off at a grocery store.
Others say renting a one way car rental can be the cheapest, but it might take a bit more time doing the waiting at the counter, you also have to worry about the directions to the port, and then returning it to the rental agency (or parking at the port if you book it as a round trip).