Hi Mantas,
I think it doesn't matter where you put your models, because buyers doesn't search by category, but rather by keywords/tags, so if you'll sort your keywords correctly, the buyers eventually will find your models. Categories are meant for casually browsing people mainly and to create illusion of order. Categories are nothing more than special keywords in cgtrader anyway. But if you still want more clarification on categorising, you can think that way - if model is raw scan, then put it under scan category, but if it's processed in any way, then put it under more specific category.