The best AC for me is the one that really makes a difference given the airport atmosphere. I certainly like LAX and JFK for the same reasons above. DFW - I can't complain. Ditto for ORD.

Regardless of staff, these 3 stand [stood] out:
Before they closed it about 8-9 ? years ago the DTW AC made a grim terminal experience civilized. SJU and MIA for the respite aspect.

Because of staff, these 2 are [were] always a plus: DCA is pretty small but it's nice because the bartenders make bloodys from scratch and use Old Bay
FRA was also small but nice and quiet had a nice staff too. Was there in November on Priority Pass via AMEX and it's still a nice club. I actually liked its atmosphere better than JAL.