Mechanical System Identification [simulation and prediction]

I have basic knowledge about system identification. I have a mechanical model , it has 3 inputs and 2 outputs. I got the data; inputs and outputs signals, I am trying to get state space model to design a MPC. I performed system identification, I got 2 systems the first is simulation focus model, and the second is prediction focus model. my question which one should I pick and go on for controller design.

Second Question, I plot both systems with the output signals, when I change from 1 step prediction to simulation the models do not fit the output signal at all. Why does this happen and does this help in picking the right model ?

Kind Regards,

Anas