If they ever actually put The Silmarillion to film, I'd like to see it done as a semi-anthology TV series. Each season would primarily focus on one of the major tales (Fëanor forging the Silmarils and the Noldor pursuing Morgoth into Beleriand; Beren and Lúthien; the Children of Húrin; Tuor and the Fall of Gondolin; Eärendil and the War of Wrath) but storylines involving various other characters would continue throughout the whole show. Movies would be cool, but I think you'd need at least one for each of those big events, and with movies' limited runtime you'd still have to cut out a ton of important material.