Stewart, Washington's D stinks as of late. Houston's D is far superior against the run. Based on matchup (i've benched/started based on matchups aside from obvious starts since week 1 and has yielded a 7-1 win-loss ratio) i would start Stewart. Even though Carolina hasn't found there run game, i would still lean toward Stewart if these are your only 2 options.
Please leave feedback i am also at a xroad but in my FLEX position. Thanks in advance.