Agcl is a salt of weak base and storng acid , while CH3COONH4 is salt of weak acid and weak base so probably (MAY BE Agcl) .
Since Cl attracts bond pair of electrons towards it makin the bond polar hence dissociates while CH3COONH4 is neutral and non-polar.
more over it's(Agcl) heat of neutralisation is slightly less than 57.1 kJ. so i thnk it can a reason also.