Is there a reason you are only considering those 2? There are plenty of other choices for that route, including Virgin Atlantic. Also some people think Newark is better than JFK for getting to New York City. Are you considering economy or Premium Economy? PE has more room but may not be worth the premium price. Personally I always fly PE now across the Atlantic but I am old and I can afford it. My personal view of the PE I have flown, Delta, American, United, Virgin, Norwegian is that they are all about the same so I would make my choice based on price, available seats and schedule. First row bulk head seats are highly desirable. If you are flying economy you should also look for bulkhead seats, you have to pay extra but at your size they are probably worth it.