^^ Thank you for making my point for me with the official TFA poster. Incidentally I happen to like the Yoda-less ESB poster more than the one with Yoda, but that’s mostly because I like the coloration of that one more.
But I should clarify my original statement. I simply think that a poster is stronger when it features the actual leads in the film or visually illustrates broad themes, rather than specifically including characters given as an emotional reward to the audience at the end of the film. The same thing applies, perhaps to a lesser extent, to the ROTS poster. I feel that it would be stronger without the giant mask in the background. It doesn’t matter if you know Vader, or Luke, will make an appearance or not.