I don't believe that ValueList and ValueGroup are deprecated, but I would not implement any new data structures using these. Rather, I prefer a Page List or Page Group property typed to one of the subclasses of SingleValue-* (e.g. SingleValue-Text, SingleValue-Integer, etc) where I need a list of scalar values.
This of course doesn't help you in this scenario, as you are dealing with the data model of a Pega OTB class.
Although you'd still need an Activity, consider implementing a Data Page to represent the Value List / Value Group data on a Data-Admin-Operator-ID as a Page List / Page Group. This way if you have multiple features that need to iterate over this list, you incur the 'debt' of implementing an Activity only once (at the Enterprise layer), and every subsequent feature can use Data Transforms to iterate over a Page List on the Data Page to reference this repeating information.