I'm redeeming in F to JFK in June and I'd like to know which of the above flights people consider better.

BA113 dep LHR 15:25 arr JFK 18:05

BA115 dep LHR 16:10 arr JFK 18:45

They're both operated by 747, so really my main concern is arrival at JFK. I'm wondering that if I get the second flight then there may still be economy pax from the first one gumming up immigration and customs etc. Would this be the case (assuming both flights on time)? I've only arrived at T7 at JFK once before but that was on United and it took a while to get through. My second concern is that if I arrive on the first flight, it might still be rush hour in NYC and getting into town may be a problem.

I realise that these two points are really diametrically opposed (i.e. a delay in the airport will probably lead to less delays on the roads) but I just wondered what people thought and whether they had a preference. The choice is only between these two flights (award availability wise) and it will be a Wednesday afternoon, for what it matters! TIA.