You do not specify single frequency or multi for the Park and Field modes but I am going to go out on a limb and believe you are asking about Multi - frequency for each of the modes you mention. After all, I feel this is the main reason most purchase the Equinox. I primarily use Park1 Multi and I have had tremendous success in finding silver. Others will give their experience of what works for them. In the end Its best to find a target that you feel is silver (ex. a silver dime for me usually comes in at a TID of 26) then switch modes in multi-mode and see how each mode reacts to the potential silver target. If you are truly inclined, you can even go through all the single frequencies too. I performed a ton of testing my first season and Park1-Multi (hands down) beats the other modes you mention on deep and questionable silver targets. Field 2 comes in 2nd place. I find Park2 and Field1 absolutely useless.
I am going to throw Mkus into this conversation because he has tremendous success in finding silver with Field2. Like I mentioned above, perform testing of the different modes and then you can make a determination of what works best for you.
Park 1 Multi-IQ processes a lower frequency weighting of the multi-frequency signal, as well as using algorithms that maximise ground balancing for soil, to achieve the best signal to noise ratio. Hence Park 1 is most suited for general detecting and coin hunting.
Park 2 is better suited for smaller targets and greater trash densities. It will detect a wider range of targets including low conductors (or higher frequency) targets, e.g. fine jewellery. All non-ferrous targets are accepted by default. Recovery Speed is also increased to clearly identify good targets masked by iron trash
Field 1 is for general hunting with high trash rejection. This assists in locating desired targets more easily. The default discrimination pattern is set to reject Target IDs 1 and 2 (most coke signals).
Field 2 suits locations with high target and trash densities. It will better detect small hammered coins on their edge or at greater depth. The default discrimination pattern is set to reject Target IDs 1 and 2 (most coke signals).