I haven't used the NWN toolsets so I can't comment about them directly, but IME the Divinity toolset (which has an undeniably steep learning curve) sat somewhere between the TES Construction Set, which was probably the most accessible and easy-to-use overall (though it had its own problems such as being very crashy and creating very dirty plugins) and the Dragon Age Oranges Toolset which was just horrible even when you did figure out how to use it. And still crashed a lot. :|
I must admit to being a little bit surprised at the apparent lack of mods for the Original Sins though; I'm wondering why it didn't take off more than it did as modders tend to put up with all sorts of evils and there were some very good third party tools available. I hope that BG3 proves more popular with the modding scene.
