These are completely different dinning experince's, to say the least. We have eaten at both and we were not thrilled with either's offering of crab legs, but if I had to pick one it would be Cape May.
Fulton's - the riverboat is fun and a nice enivorment - but I agree with another poster that is was not really clean, in the dinning room, now the bar area for us is nicer and offers good drinks, and appetizers. The service is not very good, very snotty server, she acted like she was doing us a favor, on our 2 nd try not as bad service, just did not seem to give a flip, but at least brought us our food and kept our drinks fulls. For us we feel it is over priced for the amount of food you get and the cost
\\ We had dinner and walked around DTD, but on the Bus ride back to the resort, DH said I am still hungry, and I answered me too, so we headed to the food court, The shrimp Po'boy was better than the food from Fulton's that night.
Cape May - cute themeing - very clean - For a group of people it does offer more options for dinning. We enjoyed it all times that we have eaten here. You will get more for your money and leave full. Only once were the crab legs just not good, but more often they are good. For us this has worked out, as sometimes with a group, someone doesn't like or might have a shell fish issue, here there are lots of other choice's.
If you have a car and really want Crab Legs, there are lots of good offering near Disney to try out.