They both USED to be better than now.
Coachmen was bought by Forest River and quality has gone down since.
Jayco has always had problems, most specifically not that long ago with massive roof rot that lead to the entire roof collapsing if not fixed. But, Jayco was recently bought by Thor of all companies, and Thor is notorious for absolute abysmal (lack of) quality, terrible construction, cheap parts, wiring fires, and laughable customer "service" that can be appallingly bad and flat-out insulting.
So, it's a crapshoot. I'd probably go with Coachmen if I was pushed...I'd still reluctantly trust Forest River more than Thor any day.
It's kinda like the choice between stabbing yourself in the foot or stabbing yourself in the hand. They are both gonna hurt, you just gotta figure out which type of pain you can handle the best.