I haven't come across any out of the box function to check the maximum ocurence of a value in a page list.
Without writing custom java you can write an activity to get the max occurence of a page list.Please check the below sample activity and modify it accordingly.
1. I have a Source list which are some instances of the Assign-Worklist.I'm trying to get the pxAssignedUserNames max occurence.
2. Logic is to loop through the Sourcelist and get the count of a specific value and append this value with Number of occurences to a new list (OccurencesList).So you will get all the unique values with number of occurences in the new list.To avoid going through the same value again we can check whether the value of source list is already existing in occurence list and skip the iteration.
I have used below condition in the step 3.1 (@Utilities.IsInPageList(.pxAssignedUserName,"pxAssignedUserName",OccurenceList.pxResults))
Create occurence list with the Count of each value. (@Utilities.countInPageList(Local.AssignedName,"pxAssignedUserName",SourceList.pxResults))
3. Sort the count property of Occurence list in the last step to get the maximum number as the first entry.
Note : I have used existing Assign-WorkList class and properties and you can add the properties as per requirement.