The Chosen One??

I know Lucas always intended for Anakin to have been the Chosen One, but in Rebels, Kenobi seems to believe that Luke is the Chosen One.

Who do you think was the true Chosen One, and why?

Anakin as made clear by the Mortis trilogy. Filoni explains that Kenobi was wrong about Luke being the chosen one.
https://www.inverse.com/article/35969-star-wars-anakin-luke-chosen-one-obi-wan-rebels-season-3-bluray

Yeah, the Chosen One was Anakin. That was the intent of GL and Filoni, and from an in-universe POV, even The Father was sure of it.

Kenobi had essentially lost all faith in Vader after RotS, and personally believed Luke could fill that void and become what Anakin could have been... But he was not literally the Chosen One. Luke was just the #NewHope