Historically, Romo has torn Washington up. He's got 6 tds and 1 int in two games (1 home/1 away) with a 4 td game coming last year in Dallas. That being said, Oakland is horrible, but may surprise San Diego who's heads are probably huge from their blowout win vs. NYJ. Rivers is not going to throw 3 tds every game, like he has so far.
Its really a toss up and you probably can't do wrong with either. My suggestion: Romo.