Tried the Airtrain on 2 occasions only to discover it is more expensive but no more convenient or faster than other alternatives.

I traveled Airtrain Jfk - Jamaica in the late weekday afternoon, then used the E train($7.) and probably arrived at 74th/Bway, Jackson Hts a little faster than Q-10 to Kew Gardens and E train($3.)

Returning to Jfk late morning from midtown, waited 20 minutes for A to Howard Beach,
then waited at least another 10 minutes for Airtrain($7.), A to Lefferts Blvd and Q-10 would have been faster($2.).

The only advantage with Airtrain leaving the airport seems to be for those going to Long island or Penn Station.