Everything else being equal, a fifth wheel should tow better. Having said that, I would never trade my 34' silver Avion for a fifth wheel because I don't want to give up the truck bed. I take at least one quad with me and I don't want to pull two trailers. The Avion pulls so nice that usually I don't even know that it is back there except for pulling long hills. I have pulled that trailer across the country several times and I have never had a sway issue or any ill handling characteristics. I use a quality WDH but I don't use the sway bars. I've never had the need for them.
Which one is best? There is no "correct" answer. It all depends on what the user wants.
I recently put my Avion C-11 on a trailer made to take a quad so that I could put one quad in the back of the truck and the other on the trailer. It is kind of a red neck toy hauler, but I can take it back off road quite a way without getting hung up on a rough road. My 34' Avion would never get anywhere near as far back as I want to go. That is why I no longer use it.