Welcome to the cafe!
I'd go with.
QB: Newton - better match-up and he's on fire. Ride him while he's hot.
RB: McFadden - every week he plays, no question
RB: MJD - he's the only offense JAX has and decent matchip
RB/WR: Matthews - I always play extra RB when I can and it looks like Matthews is starting to get it going
RB/WR/TE: Hightower - seems to be the man in D.C. (and always play extra RB - they touch the ball more than anyone accept the QB)WR: Marshall - best WR on your roster, Henne and him look to be gellin'
DEF: Titans (I change it weekly)