I think ideally, suggesting based on context would be best. If it can detect what class or object precedes the marker and suggest the appropriate set of methods, I think we would have a pretty good autocomplete package.
For example, if you start with $page->, locale() shoud probably not be part of the autocomplete results as locale() is used on $language objects and on the $site object.
@distantnative Do you want me to share what I started?