I think I would still play Antonio Brown vs. the 49ers. He has surpassed M. Wallace as the #1 receiver on that team, and the 49ers run D is much better than the pass D, so you have to remember that. It's a risky play with the Big Ben ankle situation. If you do play Brown, I would definitely sit Spiller. The Bills offense on the whole has been terrible the past few weeks. Also, Miami is a decent/good run D, so I don't see much from Spiller or the Bills in general.
You have to start McGahee vs. NE. That entire defense is crap. Helu went for 120+ on them yesterday. The Broncos are a run first team, so McGahee will be fed the rock. Finally, I would not play Greg Little against AZ or for the rest of the season. The Browns offense is bad, McCoy is concussed, and Little likes to drop passes. So A. Brown and McGahee for me.