Addai sounds like the safest choice. SlimWhale will probably get 35 yds and a TD and his upside is limited. I think Addai will have a chip on his shoulder and will produce fairly well this year.
1st game prediction - 70 yds and a TD. But he has the potential to do more...
2010 12-team .5PPR
QB - Ryan, Vick
RB - S. Greene, Forte, Stewart, F. Jones, Sproles
WR - Moss, Megatron, NYG Smith, Floyd, M. Williams (TB)
TE - Cooley
D - CIN (week to week)
K - Bironas