Mace Windu Vs. Sion
Who would win
Location : StarForge's Bridge
Duel 1 - Force
Duel 2 - Saber
Duel 3 - Melee
And take this into Consideration as it comes from Wookieepedia
Sion was a uniquely powerful Sith Lord, having learned the ways of pain in the Trayus Academy on Malachor V. Torturing and killing others helped him enhance his strength in the Force, and his ability to feed on his own pain and hatred made him all but immortal, as when he was struck down, he could always arise, feeding on his agony. He was also a lightsaber master, and arguably the most infamous and deadly Sith Assassin of the era. Sion was known to be responsible for the deaths of countless Jedi during the shadow war waged by himself and Darth Nihilus.
Having lived so long knowing nothing but hatred, Sion was glad to leave it behind for good. Interestingly enough, because of Sion's command of his own pain, saber skills, and preternatural ability to survive through the dark side, the Exile was unable to defeat him in lightsaber combat, but forced to use persuasion to turn Sion against his own beliefs. The Exile eroded Sion's will and convinced him that Darth Traya had no more use for him, and by giving up the Force he would finally be free from the horrible pain and hatred which he had condemned himself to.
Sion was a master of the dark side and certainly knew how to inflict pain and torment on those unlucky enough to face him. He was an exceptionally skilled lightsaber duelist and had learned to channel his pain through the dark side, making him nearly immortal. He also used the advanced version of the Force power Drain Life, called Death Field, and Dun Möch, using all of these skills with peak deadliness, making him a brutal and vicious adversary.