BTW, we seem to be talking about a "shot-everything/light units only/medium units only/heavy units only" toggle.
However, I think that a "shot-everything/mediums and heavies/heavies only" toggle would be more useful.
I mean, plenty of units with slow reload times have good reasons to not shot light and sometimes medium units. But they're rarely going to have reasons to shot mediums but not heavies.
The currently proposed targeting system would be inconvenient if you want your lance to not shot glaives, to shot knights, but still shot dantes as well, for example.
Meanwhile riot units already seem to do a good job of prioritizing the close raider over the more distant heavy unit. They don't need a toggle making them fire at light units exclusively.