Here is how I choose my transportation to the port:
If there are only two of us:
From the airport to port, we use the
DCL bus.
From Disney World to the port, we use a towncar service.
For three or more people, it's worth it to use the towncar/limo service for all the perks.
We have had good experiences with DCL bus service. The only drawback for us, is that the buses from the resorts to port, do not leave until around 11:30 am - 12:30 pm, and we like to arrive at the port earlier.
On our recent trip, we used Southern Elegance from the airport to WDW and from WDW to the port. We had very good experiences with them (Leonard is great!) and plan to use them again for our upcoming trip from airport to Cocoa Beach hotel, where we will stay prior to the cruise. We plan on using the DCL bus from port to airport this March, since it's only two of us, and it's really very easy and sort of fun, if you have a nice driver. We used the DCL bus from port to airport this past trip and had an excellent experience with our driver, Bruce. This guy is tops!
Hope this helps,
Tink