I was about to say something similar, but in JFK there's no FL anymore. It's SoHo or Greenwich based on status. The Emerald version of that is much better than a FL, but the OP doesn't have their status listed in their profile, so hard to know if DFW or JFK is better for lounges.

I think if no OW status I'd go via DFW for the shorter connection but if Emerald then might go via JFK for the better lounge, additional buffer, plus can eat a better meal in that lounge and sleep more on the flight if desired. I personally find JL's food to be seriously lacking most of the time, so would prefer the food in the JFK lounge to it any day.