Which one has the better dealer? I've run a Deere 450G and I own a Case 1550 dozer. I can't compare the same sized dozers, but can say that Case can be difficult to get parts. They stop making some parts for their machines and if they don't have it, you are out of luck. I've had to go to salvage yards for my Case Dozer. I will say that the guys who work there went to a lot of effort to try and get me the parts I needed, but effort wasn't enough. My engine is a Cummins, but you can only got through Case to get parts for the engine. Case and Cummins have an agreement that if you use the engine number to get parts, a parts store like Napa or ABC or even a truck dealership cannot find any information on that engine. It's like it doesn't exist. Having said that, the price for engine parts is as good or better then the parts stores when I compared things like a new Turbo and bearings.
On the Deere, it also had some issues with getting parts and only being able to go through the dealer to get them. I don't have anywhere near as much experience on the Deere, or wrenching on it, but found that they where about the same as far as getting parts and what you pay for them.
So it really comes down to the dealer.
Eddie