Car service all the way.
It is a minimum $15 charge to go to/from NY to NJ (either way) in a taxi, as they have to go back empty. And you have to pay tolls for the taxi for the return. I learned that the 11 miles trip from my Chelsea apt to EWR one early saturday morning, even though the actual fare was ~$30, the tolls and the surcharge for going into NJ in a NYC taxi brought the charge up to ~$60. Car service (212 444-4444, 212 666-6666, 212 777-7777 for examples) can take all three of you for a fixed rate, no surcharge for going into NJ and one way on the toll + tip. I think the fee starts at ~$45 ish + tip + toll. You might find a coupon in the plane magazine or at the "transportation" cards in the baggage claim area in the airport. You can call when you arrive at the airport and they arrive in ~10-15 minutes.