The fly by wire computer system would have made a ditching more easy with less likelyhood of a stall, unless the loss of electrical power with the loss of engine power put it into direct law. So the aircraft is solid for this kind of problem.
The crew would have little time to think. They would just be following their training. When they were unable to get back to La Guardia a ditching would be the obvious choice with all the buildings around on land.
Some would say that ditching at 140knots or so would mean it would tip over with the underslung engines. That didn't happen. Maybe the engines ripped off at their connecting points. That loss of weight could account for the aircraft floating for so long.