I have all of them, almost.
I have a compound feed (needle feed, walking foot with alternating presser feet) Singer 211U I use for canvas and upholstery. LOVE IT, LOVE IT, LOVE IT!
but.... because I sew heavier things with heavier thread, usually V92 or V138, I have a stonger tension spring in the tension disks. With the strong tension spring, I can not relax the tension enough to get it right with the thinner V46 or V30 thread used for camping gear....so I don't use it. Also, timing it is much more complicated than with a standard drop feed machine.
I have a walking foot LSZ-1 Sailrite that works great for heavy stuff and works OK with nylon if you change the feet to some that are less course than the toothed feet included with the machine. It's just too slow for my preference at 800spm.
I have a drop feed Bernina 217 that I use for the majority of my gear making. It works great but parts are EXPENSIVE. I just sold my Singer 20U that worked great and parts were reasonable.
I have considered getting a drop feed + needle feed machine like the Durkopp 212 because I can get one reasonably priced, but just haven't pulled the trigger because I don't really have the need for "single purpose" straight stitch machine now.