Gooseneck hitches use 2 5/16" balls and are generally used in Horse, Cattle, and Equipment trailers. I can order Cargo trailers with either. You won't really notice the difference in towing, because both are mounted just in front of the rear axle. With Gooseneck you have to use safety chains. When the govt. was discussing chains years ago, the RV industry fought against them and won. There is a gooseneck adapter for fifth wheels, but it will void frame warranties with a lot of companies.
My opionion only: Fifth wheels are easier to hook up because you slide the king pin in compaired to lifting the ball coupler over the ball and then lowering it onto the ball with most couplers. There is a ball coupler you can back into and jaws go around the ball, but you have to back in straight, not at an angle. Another thought, most gooseneck trailers use manual jacks and most fith wheel campers have electric jacks.
The only benifit of a gooseneck in my opinion is that you dont have fifth wheel rails. The big dis-advantage is that instead of putting all the weight and pull on a larger hitch you put it on a single 2 5/16" ball