Both one man armies and both have lifetimes of expirience on the field. Hm.......both human (counting marston as human) and in a REAL scenario no health regen for marston and not some quick draw showdown thing going on like an actual fkin fight cuz then of course marston would win. Im talking about a gunfight here. No body armor for niko since John doesnt have any. Both are ridiculously accurate and what john has in dead eye niko makes up with modern weaponery (bullets travel faster now then they did back then) In conclusion......fuck it! Who knows? I love both guys equally so im not being biased and I just honestly dont know. The only thing i do know (and we can all agree on) is that it would be a VERY close fight. There wouldnt be a "hands down" victor. In fact, I think they might both die. One would win the battle right? But he would be very badly injured and both men have taken many bullets before and walked away but in this case...with no outside help.....im thinking this would be the graves for both of em.
John would win doesn't matter how advanced the guns are its all in the draw and john can do it faster. lets think for just a moment in the duels which I think would be a fair form of fighting for these two. The duels start out in dead eye letting him pick his moment but go into real time proving hes a faster draw and shot perfectly capable of disarming people if not killing them with deadly accuracy and speed. at the end of the day fancy guns don't mean shit if you ain't fast and dead is still dead. Also body armor won't protect shit if john scores a head shot which he usually does John would win hands down.