Until the Panthers start getting their running game going, seems Smith and the TEs for the Panthers should be getting decent numbers. Usually would be afraid of rookie QBs until they have played several games, but with Newton it seems he isn't being restricted.
I have Johnson and had him last year as well. He is pretty productive as well, unless he is cursing God for his TD drops. Fitzgerald is producing good numbers as well, but the Bills also have far production from their running backs.
Safe play for me would be Johnson, so that means you should play Smith. I stink at FF. Nnamdi is having issues with Philly's defense and isn't as dominant as he was with the Raiders. That will change but not sure it happens this weekend.