Olynyk and Sully get my vote, at least for a little while so they both can build confidence. Then I would hope Brad goes back to the flex lineup based on lineups. Bass replacing Oly for quicker PFs, and then Zeller for quicker Cs (along with Oly if the PF is too fast for Sully).
I know Bradley will start at the 2, but I've been liking Thornton there ever since we got him. Rondo would obviously be better off with the best scorer/shooter, and Bradley/Smart just seems like a strong duo.