Any of the above is fine, but your decision is usually based on the following:
How many people are in your group?
Are you flying in same day or day before?
How pressed for time will you be while traveling to the port?
What is your budget?
How comfortable do you want to be?
Hypothetically, if we arrive the day before I choose to rent a car since I know the way to PC and the hotel we would be staying until the cruise the next day. It is cost-effective and we get to do a little shopping and sightseeing the day before.
If you arrive the same day (most would not recommend this option) then I would get some form a dedicated transportation whether it is a rental car or town car service since I would want to get to the port right away.
If you have a large group (more than 4) then a town car may not be feasible, but a limo may be more than you want to spend so you could get a shuttle/van dedicated service for around $100.
If you give more details on your travel we could provide more accurate information.