Bouncing between two PhD supervisors
This seems like a mixed blessing/curse to me. It seems to be hard and frustrating, of course, but on the other hand you have two professors who, while not agreeing on much, seem to love your work. You get a lot of finalized work (publications) out of the deal. I suspect you are building a strong academic career for yourself. 

But I suggest you look for the end of the tunnel. Get the main work done somehow and find a good position without alienating either of your "patrons." I suspect that you are in a strong position in the long run and quitting would be giving up too much. 

I suspect that you are pretty good already at putting the two off at least a bit to make some room for yourself. If you can continue that, then just start to plan your exit. You won't be juggling their needs forever, I think.