Efron? Eww.
Still, rather him than Miley Cyrus or any of the other live-action Disney crew.
Obviously, I hold out hope that Harrison, Carrie, Mark, Kenny, and Anthony will reprise their roles - although it would be nice to see Peter, the role of Chewie could, given what occurs in-established-expanded-universe, be in some dispute, depending on when the movies take place in-universe. It also, of course, depends on whether they make use of the already-established expanded universe, although I do hope that if that is to be the case, they make nothing more than a mention of Sidious beyond Episode VI.
My choices for other actors? Well, it all depends on what roles they have that need filling.
For example, an old and wise Jedi (assuming that the movies include some focus on Luke's newly-established order) mentor in the series could easily be played by someone like Ian McKellen, who could also be a badass in all the right situations. A cool, calculating Admiral on the side of the villains could be played very effectively by Ralph Fiennes. If the Mandalorians were to get involved (because there always seems to be a Mandalorian somewhere in a Star Wars saga/derivative thereof), it would be nice to see Temuera Morrison finally in-person in the role of Boba Fett.
Other actors, whose roles I can't quite picture at this stage, I would like to see are:
David Tennant.
Warwick Davis (although not in the capacity as an Ewok).
I am in accordance with the propagation of Alan Rickman.
John Hurt.
(Very hard to come up with a list that isn't, in some way, linked to public appreciation/fanatical following)
It would be quite amusing to see Zachary Quinto and/or Chris Pine have some role in this film saga.