I'm flying into the US on Aer Lingus from the UK and must switch to Jet Blue for the final leg to Portland, OR. For the same price, I can either make the switch at JFK (2hr 50min layover) or O'Hare (2hr 25min layover). Which airport is the best choice? Will I have to go through security in either airport for the airline switch? Is one preferable in terms of getting to Jet Blue from where I will clear customs? My baggage will be checked through in either event. Thanks!