I would have to say unknowns for the most part. Now if the actor is an alien you might get away with it nothing to recognize.
Recognizing an actor from another movie tends to break immersion.

Combination of original cast, recognizable character actors, and for the young leads who will inherit the mantle of Star Wars, really fresh faces.

I agree with the above. There should be some unknowns and some recognizable faces, but no mega stars unless absolutely necessary.

a combination...the way it's always been:

OT: Alec Guiness and Peter Cushing
PT: Liam Neeson, Ewan McGregor, and Natalie Portman

There were also some lesser-known and basically unknown actors in both trilogies. I want the same for this one. In terms of established actors, I'd love to see Gary Oldman and Michael Fassbender in the new trilogy.

Throw in one or two super fan actors who petition for a bit part, e.g., Samuel Jackson and the ineluctable cameos by friends and family of Disney execs and you've struck upon the best casting we can hope for.

I agree with many of you. I think having one or two well knowns and the rest being unfamiliar unknown actors, similar to a ANH would be best. In a similar post I said that I wasn't too fond of Haydens performance as Anakin especially when turning into Vader. In this case I feel as though they took an unknown actor and as a result ended up with a subpar performance.

The only cameos I really want to see are Sam Witwer and James Arnold Taylor .