I'm still not 100% sold on Barnes. I'd like to see him become a natural scorer as well as a shooter, a more versatile player. But there's no question that his shooting stroke would put pressure on the defense and space the floor for Favors and Kanter.
I go back and forth on Marshall vs. Lillard, but I'd take Marshall if he can become an adequate shooter. I just look at the Bulls and think how much better a team they'd be if D.Will were the point guard instead of Rose. I know Rose is an elite scorer, but D.Will would make Deng, Korver, Boozer, Brewer and Noah much more effective. Marshall has that ability to move the ball. He needs to be more of a driver and scoring threat to give that passing more credibility, but I think he can probably do it.
Edit: If I had to choose between Marshall and Barnes, I would probably go with Marshall. Hopefully we can find a way to get both.