I think it would be a draw. Don't automatically come up with your answer. Listen to my reasons and you will see. This is the best way. Ish. I don't know but Darth Vader turns good... Lets just exempt this good part. And Voldemort? He's all evil no exempting for him.

OK so the basics:

Location: Earth, place where Voldemort and Harry duel in the forest.
Time: Dawn (Duel before the sun is in the sky, pick a place to die where its high and dry!)
High Ground: Darth Vader


OK So here it goes!!
"You weakling I HAVE THE HIGH GROUND NOW OBI WAN!!!" Over in the corner Bellatrix Lestrange looks at him like he was from her favorite type of movie. A horror movie (of course.) The duel commences. Unforgivable Curses fly Light sabers flash, The force chokes. Darth Vader deflects, Voldemort sends, but by and by a winner seems to dig through the sand getting closer and closer t the crust while the other slips to the magma to ultimate doom. Darth Vader has crushed organs that have been revived. Choking nearly pulled him down until the final slip up.
Darth Vader moves to throw the saber and choke as the last killing curse ever made from him fly's from Voldemort wand right towards the now defenseless Darth Vader. With a splash they fall to the muddy ground defeated once and for all. Darth Vader killed by spell, Voldemort gone by decapitation. This horrible event of affairs made us see, not one is above not one is behind. No matter what you see this is how it might always be. And isn't Harry better now? Perhaps Sirius didn't die. And now well who knows what will happen but the villains are gone and that is for certain.