Both AP and Marshawn had amazing rookie seasons. Probably the most impressive thing that stands out in my mind about marshawn is that he was able to put up the numbers he did when everyone in the league knew that we were gonna rush.
They are different styles of backs though, AP is more explosive, speed, finese. Marshawn is a run your ass over type of back with good speed, great hands, and bulldozer like drive in the legs. It is just amazing watching him keep those legs churning grinding out those extra yards.
I would be happy with either of them on my team. Marshawn wins though because #1 he is a bill, and #2 he just seems like an all around great guy. His interviews are awesome and fun.