I like row 62 or row 64 on the upper deck, or 14k on the lower deck. Immigration in JFK is always busy unless you're on the LCY flight where it's a domestic arrival and much quicker. 13.55 is quieter than 9-11am or 4-7pm but still quite busy. Many flight land at JFK, the extra time saved in disembarking will not amount to much come immigration.