Another of those questions with no real true answer, Kinda like the Frod vs chebby vs dogde vs _______ question. OR what tires, be it brand or tread design, which motor, gas vs diesel, or size of displacement. Which rear axel ratio..........
I had a tt as I could home from work, with my lumber/ladder/wood/pipe rack on the truck, hook up and GO! Try that with a 5W! or I could load a canoe on the rack and go too.
Reality is, ANY trailer, be it a bed mounted one, like a 5W or goose neck, WILL sway just as bad as a ball/pintle hitch set up if they are loaded incorrectly! If you need a special hitch, ala Hensly or pull-rite to keep a given trailer straight behind you, you have other issues that make that trailer unsafe. Just as I have seen 5w's that were wiggling side to side! as I have seen and felt ball/pintle hitch setups go side to side when loaded incorrectly!
There are too many variables as to how any one can say, a ball or 5w is the better trailer per say. As there are about as many variables as to how you use a trailer also! Then there is floor plans, useage etc as to which will make a better Towing rig! "Better" can be used in many different ways mind you!
Take the poison pill of your choice, enjoy it! That is the best one can say on this issue frankly!
marty