The Colts don't need to win a single game for their WR to be useful. Branch will be one of at least 5 guys getting the ball. So unless anyone thinks Brady will be throwing for 500 every week, it's pretty much a wash. Collie of course has brain issues, but we knew that before the draft.
Branch has no upside. What you see is what you get. IF, big IF, Collie stays healthy he is the better option even if Joan Collins is the QB. Neither player however will be the difference between winning your league and losing, so it really doesn't matter.