Unfortunately, I'm in a similar boat.
Kelley is @ Sea who are good vs the run, Washington's O-line is beat up right now, he is a little banged up, and has really shown nothing other than the TD last week.
Lacy has a slightly better matchup vs Was, but Sea has no O-line either, and Lacy has shown even less than Kelley. Seattle coaches say they want to give him the ball this week, but I trust what they say about as much as a politician's promise.
If I had to pick between the two, I'd go Kelley, hold my nose, and hope for a 1-yard TD.
Other 1-week options I'm personally considering who may have better "upside" this week are Gallman (vs Rams), Booker (@Phi, yikes), and DeAndre Washington (@ Mia)...