Unity is a lot harder to program in, it doesn't have all the basics for a VN that Ren'py or RPGM have so it you are a proper dev you have to make them but this is porn so most of these Devs can't actually make a back button to scroll back in Dialogue because it is easy to skip a line now and then or miss read something and the subsequent dialogue doesn't make sense and being able to reread a scene helps greatly in a NOVEL even a VN. But our Tech demo doesn't show us that the Dev can do this. Unity can do this but you actually have to know how to code and it isn't provided ready made in the engine.
So you're just saying you know not a damn thing about Unity, or Ren'Py.
Ren'Py REQUIRES programming, and even pretty tedious programming to do the smallest thing.
Unity does NOT require programming if you use the visual tools.
Also, a VN can be made using either Fungus or Naninovel if you don't want to program the tech yourself. BOTH supersede Ren'Py in functionality and graphical abilities, vastly.
Also...
Ren'Py will fucking ... never ... be able to do fucking 3D.
In the end, once you set up your concept, it is MUCH faster to do a VN in Unity than in Renpy. Also, Renpy is still based on Python 2.7 which is 12 years old. And it requires runtimes for each game you have, ranging in size from 80 to 500 MB. And that's without any game data.
End of discussion.