Definitely Nightmare Luffy!

nightmare luffy will win, but he looks like a horrible blue hulk

Jozu.

Why do you think that Jozu would win? I'm curious...

I don't know who Nightmare Luffy is... I saw that Jozu was strong enough to face off against Aokiji, so he can't be weak, hence my pick. XD

It's impossible to say with any certainty, but given the evidence we have on hand, Jozu should be winning this outright, and I'm shocked he isn't. Luffy was up against an incredibly large opponent, to be sure, but Jozu proved he's just as strong, if not stronger, without the use of his Devil Fruit. Nightmare Luffy depends on two styles of attack: blunt, physical strikes, and the sword he wears. Even if we assume that Nightmare Luffy could hold to that form infinitely, he's up against a man made of diamond. Mihawk couldn't even cut him, how could Luffy hope to accomplish such a feat? Luffy's blunt attacks would be like slamming his hands over and over again into a wall of diamond. The only reason Aokiji defeated him was because he attacked Jozu in a different way, freezing his body and thereby cancelling his ability.

Few Nightmare Bazookas and defense zero.. I mean cmon he defeated Oz and Moria so easily.

I think you're missing the key differences here. For one, Jozu was likely quite a bit stronger than Oz. The huge chunk of ice he tore out and threw at Marineford is a testament to that. Size has a way of not really mattering as much in the One Piece universe as in real life. The Nightmare Bazookas you're talking about would be hitting into someone whose entire body is composed of diamond. Oz may have been huge, but he was still about as vulnerable to damage as any given individual. Moria's abilities really afforded no extra protections, and he viewed Oz as his strongest weapon, so he was entirely dependent on his strength and inability to feel pain. Jozu is literally made of the hardest substance known to man. The strongest slash in the world did nothing to him. Why would Luffy's bare hands work better?

nightmare luffy can crush any diamond guy

Jozu took on aokiji, Nightmare Luffy would be pushed to the limits by a powerful marine like doberman or onigumo.

^Jozu didn't and will never take on Aokiji - he was easily beaten.

^ Only because he got distracted at the wrong time. He was doing pretty well prior to that.