For Good guys:
Ezio. Not as successful as Altair, he still rebuilt the brotherhood and got the apple.
For Bad guys:
Rodrigo Borgia. Serious, this fat guy wouldn't die even though five Ezios were coming at him at once.
Ezio: "Rest in piece, you **bleep**"
Rodrigo: "I DON'T THINK SO!"
Altair. The Assassin brotherhood was in ruins, and Altair came and made it prosperous and powerful. He was born into the brotherhood, and devoted his life to it. Even on the day of his death, he protected the Apple of Eden by hiding it in a vault.
He was legendary.
WHAT HE SAID!!!!!!