With two RB spots on my fantasy team, which two should I start: Forte, Slaton, Addai?

Definitely go with Addai, but I say start Forte over Slaton. It may seem like a bad idea to play Forte vs. MIN, but he did alright in his first matchup with them, and has tended to do well in all his tough matchups (MIN, TB, TEN). He is the most consistent RB in the league, while Slaton has been mostly unproductive lately and even did badly against the awful CLE run D last week.