If by Fitz you mean Larry Fitzgerald, then YES you start him. I don't give a crap about the matchup and the unreliable QB, that's a top 5 WR in terms of pure athletic skill, and he's always a risk to make a huge play.
Floyd or Gordon is kinda a tossup... Neither team's QB is super reliable, although I suppose Philip Rivers > Weedon, and Cleveland defense is, I'd say, worse than Chargers. But both players are about equal, in terms of skill.
But I'd take either Floyd or Gordon over Michael Turner (bad matchup, as Eagles are good against the run, and Turner's a sap), and over Shonne Green (one spectacular game, does not a great RB make).