Stats aren't everything, but I think Garrard > Orton/Kolb.
Orton's nothing special who benefited from his system. Garrard's slightly above average. Kolb's largely unknown, with some upside left, and he brings a little mobility.
That said, I think Kolb should be right around 80 if his individual ratings are rated correctly. Overall is stupid. And ratings shouldn't be based on stats/production. Base it on the actual skills of the players.