ORD is now closed to further DEFOs. Only JFK, ANC (FO's), and LAX will be offered.
Jumpseating on a US carrier is generally unavailable unless a Captain is feeling charitable.
Pick LAX. Better WX. Better commuting. Better chance to get more landings on the 400 (major problem, have been told the average 400 pilot gets roughly 12-15 landings a year!)
P.S. Better Mexican food than JFK.