A 10 league team, hmmm...
I would recommend keeping:
Adrian Peterson: We all know that he's going to wreck like he did last year. I can see an average of around 6-7 yards a carry, and around 85-200 yards in the first 13 games of the season. A great clutch player, and he'll probably get many more attempts on the field than last year. His injury should be affecting him less, and he should be feeling better than ever.
Matt Ryan: RGIII is a great player, and I'm a Redskins fan myself. But you should go with Matt Ryan. He was number one last year in completion percentage, has better threats around him, (expect a lot from Julio Jones, Tony Gonzalez AND Roddy White) and less interceptions. While rookie quarterbacks first go to the NFL and interceptions are thrown often, he will cut down. However, Matt will probably have less to. I can see Atlanta getting farther than last year, so Matt would be your best bet.
If anything, and you decide to get a WR, go Steve Smith. Hes still got a lot inn him for a vet, and I could see this being in his last years playing. If don't feel like going for the risk of losing points through interceptions, Steve Smith would be a great reliable choice.