If Jackson were playing a different team this week, I'd say go with Jackson, because I think Leon is a bad play this week. The problem is that Jackson is playing one of the top D's in the league (don't let their record fool you, the problem does not lie with Washington's defense. They're five overall for a reason, and third against the pass). I think Leon is a bad play because I don't think Sanchez can pull the ninth out of the box after last week's performance... Oakland is going to test him rather than conceding the ground game. The nice thing will be that Oakland's ST unit is terrible and Leon could score at TD there, plus he's useful in screens and such. So, despite me recommending to other people I know to not play Leon this week, I think he is your best option.
Also, you seem to be new here, so just a piece of advice. Don't copy just the viewtopic part of the URL, copy the whole thing. The forum auto-formats to the viewtopic thing only as a link. If you don't do that, you make people copy/paste and I'm sure some people won't bother with that.