I ll try to explain it from engineering point of view.
soft suspension >> more under-damped than a stiffer suspension >>> falls further away from a critically damped system >> responds better to a wider range of upsetting forces (potholes in this case).
stiff suspension>> as a system is also under-damped but more oriented towards a critically damped system >> is suited for a narrow range of upsetting forces
a perfect or ideal suspension >>> critically damped system that is suited to only one magnitude of an upsetting force >>> therefore non-existent or will be under-damped or over damped different upsetting forces.
i have given a lot of key words here. read about them. best of luck