Hello,
I’ll be done any second with this pretty extensive wireframe and clay addon I’ve been working on for a long time, but I’m not sure which category it belongs to. It creates new scenes, operates in the 3D view and in the properties area etc.
This is probably not a big thing, but I rather get it right from the beginning than to correct it and re-upload it. I’m guessing it’s maybe “scene” because of the fact that it sets up a scene or several scenes, or “object” because of the fact that it basically changes the appearance of objects when rendered.
I also wonder where its panel should be located. At first I positioned it in the toolbar in the 3D view, but as it grew larger I relocated it to the scene settings in the properties area.
I wouldn’t focus on technical details, like if it creates a bunch of scenes in order to achieve the goal. You should think like a user. What is the main purpose? If it changes how things are renderd, than it could either be Render or Material. If it operates on Objects and changes them (as opposed to the objects’ data!), then use Object. If it works on Mesh objects only (so mesh data), then probably Mesh, unless it does Armature/Rigging.
If no category feels right, you could come up with your own - the categories you see in Blender are generated from all categories used by addons. If you want to publish the addon however, a new category should only be chosen if it’s a sensible new category also useful for other addon authors (and users).