I looked for an NPC mod that I really liked for a while. What I like about folks is the simplicity & customizations. NPCs can be set to use any player skin & configured to "say" different phrases. I think it has a lot of potential & could probably benefit from being able to set custom actions when interacting with NPCs.
I have come across one bug where changes to an NPC are reverted after the server is restarted. But it only occurs on the most recently created one. So as long as you create at least one more NPC, & delete it before restart, the bug can be avoided. The author seems to be active, so I am sure the bug will get fixed eventually.