There's one that I use called
Custom NPCs.
What it Does: It's kind of like Useful Villagers, but it has a lot more in terms of customization. It does a lot, so I'll just say that it lets you customize every aspect of any NPC that you create, be it Villager or Enemy.
It also lets you create easily configurable recipes and has some items too. It has much more than I can write.
Benefits: Incredibly easy to use, has dialog setup, has a quest builder, and takes very little time to create an NPC. The downside is that they can't use scripted items, like on the Touhou Items Mod.
Uses: Can be used to create non Testificate villagers, humanoid mobs, mercs, healers, shopkeepers, and "unofficial" bosses. You can also create recipes for custom items.
I only covered the basics on what it can do, so it's definitely worth a look.