I just bought a "new" used Marlin 336 (pre-safety, fwiw). In looking for it, I looked at a lot of new and used Marlin and Winchester leverguns. For me, it simply boiled down to the side eject vs. the top eject and the overall mechanism it entailed. I just liked the Marlin action better for what I intended to do (mount a small scope). The significant factors that seem unanimous are: they are both excellent guns, time-tested and proven and the Winchester is lighter than the Marlin. All other factors probably boild down to opinion.

If you are thinking of putting a scope on the lever gun, you can use a "normal" action mounted scope on the Marlin because it ejects to the side. The Winchester requires either a funky side-mount system (which I personally dont like) or to use a long-relief scope mounted in front of the breech, where the rear iron sight is. That second option is no big deal, in fact some Marlin owners do the same thing.