Assuming he gets in a "good" week of practice and does in fact play, I would go with Plummer. That having been said, I am a die-hard AND both options seem perty good. Good luck!
Brooks is the easy choice. He is healthy. He is coming off a bye. He put up 352 passing yards and 3 TDs against the Falcons just a few weeks ago. The Falcons played the game of their season against the Giants this past weekend and will certainly be ripe for a letdown again this coming weekend. They aren't nearly as good as they played against the Giants (or even the Eagles).
San Diego has a defense prone to the big passing day by the opposing QB, but this will be Plummer's first game back from injury and I'd be wary.
I would have to go with Brooks as well. Is not often I disagree with Steg. but I would want Plummer to get a game under his belt, even though its against SD. ATL will fall next week. There is no way they can do what they did to the NYG 2 times in a row.