Was Churchill the best available mentor for Elizabeth II?

Was Churchill the best available prime minister to mentor Elizabeth II because of his sense of duty?

The answer judges him the best available option, while acknowledging Attlee's qualities and the political constraint of his lacking a majority.

Churchill is judged the best available option for the role described in the question. The answer allows that one could imagine a better mentor in the abstract. Attlee is treated as a capable alternative in personal terms, but he lacked the parliamentary majority required to occupy the office. The judgment therefore depends on the choices available at the time.