I've got a 7600, 7610 and 7710. Some of the best tractors Ford made. The 7710 will use less fuel than a 2950 but will have less bottom end torque. Turbo 4 vs NA 6 cyl. The Ford is cheaper and easier to work on, and the Series II cabs are top of the line, JD is a bit cramped for me. There are folks around here that run 2955s and 3155s that swear by them, but these folks usually have enough money to pay someone else to do all the maintenance work, I don't. The JD's have impressive hydraulic power/flow but tend to have more maintenance issues in that department.
Back to your question: They are both good tractors that parts are readily available for. Pricewise the Ford should be cheaper when comparable tractors are considered. Look into service/parts leadtime for your area and buy whichever suits your taste.
cfpinz