--Update--
Darth Revan of course.
Revan was both Sith and Jedi, benefiting from the teachings of both, while Obi-Wan was nothing but an over rated Jedi Master.
I assume you mean Darth Revan, if so his default 'canon' portrait would be the one with the long hair, or mullet depending on which country you're from ;P
The Darth Revan figure is somewhat of a limted edition figure that was only released with the Anniversary Collection. The Darth revan action figure is roughly $80 now while the Darth Malak figure is about $50. If you were to purchase one, I would suggest keeping it in its packaging, as it is rare and should be kept in mint condition.
Obi-Wan's body literally became one with the Force.
Revan however, defeated the Mandolorians, Mandolore the Ultimate himself, many Jedi masters and powerful Sith, discovered nearly eternal life, was able to hide his Sith legacy from all for nearly 3 millennia and was the Dark Lord of the Sith. So Revan is by far more powerful.
Qui gon jin faced him but unfortunately he died. Then Obi One Kenobi came and defeated darth maul
because Obi-Wan Kenobi killed Darth Maul after Darth Maul killed Qui-gon Jin
Darth Revan is obviously better. He was the one who killed over 300,000 jedi in the Jedi Civil War, and lead a number of 7 Dark Jedi -in order- Mizkar, Jouran, okan, vasaril, hokan, jakur, and gokal-mannh. But his rival Malak, lead 8 Dark Jedi to the war -in order- Miska-kurrn, Mozakt-kii, Bastila Shann, Furnt-mona, Grek-gorrw, Gokk-jians, Basr-Lion, and the Exile you play in KOTOR2. Sincerely, Lord Revan :3
Darth revan sought a Great Sith lord in the Unknown Regions of the Galaxy, and he succeeded, no one knows exactly what happens after, so we will have to wait for the release of 'Star Wars: The Old Republic' to unlock these dark secrets, and find out what fate revan had endured
#1 it's Obi-Wan not Obi one you fool. #2 his master's name was Qui-Gon Jinn. #3 I'd have to say Jinn would win against Vader simply because Vader can't move around very well in his suit.
Revan is very powerful, infact he is considered one of the most powerful force sensitives to have existed in the Star Wars universe. He was both Sith and Jedi, benefiting from the teachings of both parties. He was feared by many during his reign as Dark Lord of the Sith. If it weren't for Malak's cowardly attack, Revan would have never become a Jedi again, and he wouldn't have become so powerful.
In the newer one. And in episode 4 they fought again. They fought on MUSTAFAR. Obi-Wan fought with a fully fledged Darth Vader later.
Then the sith will take over and the all the other jedi will be destroyed