Are you referring to the game, or are you referring to the manga?
If you are referring to the Four Swords manga, then I would say Vio. He's cunning and sharp-witted, but well-intent ^^
By the game, you can't really say they have personalities to go by, so I'm not sure how you'd judge, other than if one of them happens to be wearing your favorite color.
I think my favorite in the game would just be normal green Link ^^
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