I'm moving into my second Ram 3500. The only reason we are replacing our '05 was the size of the cab. It was getting too cramped for dogs and kids. I've been very happy with the Ram, and sold it to a very good friend. That being said, the Ford is very nice, and was on my radar for a bit. My second purchase of the Ram boiled down to looks, and my local dealer. I just like the look of the new Ram, and my dealer gives me awesome deals. You can't go wrong with either a Ford or a Ram.
That said, be aware of how you option it out if you are looking to tow a certain weight. There is about a 13,000 lb trailer weight difference between the differently equipped 3500s in the Ram line alone. Engine size, transmission and axle ratio all affect the final trailer towing capacity. A well equipped Ram longbed crew cab will tow a 28K trailer, while a similarly equipped Ford was about 22K. I'm betting for '15 Ford ups their numbers to compete with or top Ram. Either one will tow most, if not all, Heartland products.