I know you guys all hate me, but I'm still posting this.
Here are the conditions:
1. Saber
2. Force
3. All Out
Location: Laser Chamber on Naboo
I'm going to have to go with Vader on this one. He maybe a "crippled, half-droid, half-man" as George Lucas calls him, as opposed to Obi-Wan when he was young, but Vader is no push over.
Then again, that doesn't mean the fight is going to be easy. It's definitely going to be harder than Vader's fight against Luke in the Empire Strikes Back.
Here is my logic. After Maul fatally wounded Qui-Gon, Obi-Wan attacked in such fury that even the ruthless Sith Lord was pushed back. Darth Maul did lose to Vader, but he did gain the upper hand against Obi-Wan, and lost through his own overconfidence.
That being said, Vader would defeat Obi-Wan, but it would be an tough battle for him if Obi-Wan used Force Rage.
Listen, I'm just going by what George Lucas implies. I know Vader is powerful, even after he becomes more machine than man, losing a high amount of midi-clorians. By the way, I think people are incredibly underestimating Obi-Wan.
Darth Maul's doppleganger, who is every bit as powerful as he is, dueled Darth Vader. Although Vader was able to beat him, the two Sith Lords were pretty much even in saber skills until Maul got his staff cut in half. Then he proceeded to kick Vader's butt. Vader won through his cunning (and his near-suicidal attitude).
One more thing. When Qui-Gon was killed by Maul, I think Kenobi felt not only anger, but...fear. His master was killed, and Kenobi was left alone to fight his greatest enemy yet. But he gave into his hatred for a while and dueled Maul to a draw. His judgment was clouded, though and he was left open to a Force Push from Maul.
Never did Maul wipe the floor with Kenobi. He just maintained control long enough for him to gain the upper hand...then he decided to get stupid and gloat over the near-defeated Obi-Wan.
Both Palpatine and Vader from 6 years before RotJ survived (virtually unscathed in Palpatine's part) a blast of Force energy which killed it's progenitor and blew a hole in the Death Star visible from many miles away.
Unless you're suggesting TPM Obi-Wan can summon more power than Galen Marek, he's got butt-f*ck all of a chance.
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