It sort of depends on your definition of "best"
- most convenient is DCL transfers
- least hassle I would say DCL transfers
- least expensive for a party your size is probably rental car followed by private car service
- control over arrival time would be with a rental car
- earliest arrival at port is DCL transfers from MCO
- ability to stop along the way (for alcohol or other needs) is private car service or rental car
There are pro's and con's to each option; you'll need to decide what is most and least important for your party.
Enjoy your cruise!