Depends on what you're planning. If you plan on spending the days in the parks and just returning to sleep and maybe use the pool, then I'd stay in a resort. However, if you plan some time to "relax" away from the park, I'd select Fort Wilderness. There is a lot to do there, from just sitting at your campsite to swimming or walking the hiking trail to Wilderness Lodge. But you have to make the time.
My wife retired from Disney World a couple of years ago and we enjoy Fort Wilderness about 6 times a year. She gets a discount when available, so that mitigates the cost somewhat, but she can get a discount for the resorts as well.
When I retire in a few years we'll probably spend some time at Disney to celebrate, but it will more than likely be in a nice resort for something different.
It all really depends on what you want to do. Like I said if all you're looking for is a place to sleep, pick a resort. Very often there are discounted rates available for the resorts that never apply to the campground.