I would have said someone like Sam Niell would be a good fit for Sebastian Shaw in the Clone Wars. But depicting the earlier days of Obi-wan having to train Anakin is tougher, unless they started a prequel trilogy like 1986. Obi-wan would have to be someone like Jared Harris if they did it in the late 90s.
Sam Neill would be a superb fit. That “duality” quality he brings to that certain type of role, like in The Omen, would be interesting to see onscreen as Anakin.
Jared Harris, the actor from The Expanse and that Beatles 2-man special? I like that. Someone like him or Branagh as Kenobi in a 90s PT for sure. Heath Ledger is a name bandied about online as a possibility as Anakin, he’d be a good fit for the role and counterpoint to a Branagh/Harris Kenobi.