Buses to/from Dublin Airport - Airlink, AirCoach, Dublin Express - preference?

With 4 of you I would take a taxi. By the time you struggled on to the bus and hopefully found a place for your bags and yourselves after an overnight, trans-Atlantic flight..... Just not worth the maybe 5 euros you'll save. If you take the bus, reservations aren't necessary. You can buy tickets at the kiosk or on the bus.

No particular preference among the bus companies you've listed, but I agree with Trotter that a taxi is the way to go in your case. Cost for 4 people will be about the same, and the convenience of door to door service can't be beat... especially when horsing luggage around.
Be aware that the rental car lots are located about a half mile from the terminal along Swords Road. The airport buses only go to the terminal, so a taxi is the better way to go in that case as well.

Thank you both Trotter and Robert for your sage advice.

I am so ingrained with taking the "cheaper" way (so used to traveling with us two very able-bodied cheapskates) I forget the larger picture and greater savings really do increase when traveling with four.

We were in Dublin 4 years ago waiting in the LONG line for the bus and saw the short line for a taxi after the overnight flight. Can you say no brainer!