If money is no issue: Get a cab. If you need reliable transport: Use JFK AirTrain, leave at "Jamaica Station" and take the LIRR to downtown Manhattan/Pennsylvania Station. From there, take a cab.
Back in 2007 I arrived right on that date, when some steam pipe went off in downtown Manhattan. Whole Downtown seemed to be one single, giant traffic jam. The train ride took less than 30 minutes. The cab for the last 1.5 miles from station to hotel almost an hour ..
re: I will arrive at JFK on 31dec at noon.