The Ford Super Duty rides like absolute trash. I have a '19 and my cousin has a '20 and both are horrendous.
My father has a GMC 3500HD and it's slightly better due to the IFS but it's still rough.
Ram is the best, especially in 3/4 ton configuration because they use a 5-link rear with coils. But, the 3500 is also rough like Ford and GM.
It's apparently the name of the game, but I would say Ford is the worst. I really dislike driving mine daily. It's great with a load on it. But just commuting to work.....ugh....