Depends on what your end goal is, really. If you want to spam the SERPs while gaining traffic rapidly with thousands of pages, Vanilla PAA sites are for you - especially in harder niches - where every single long tail hit matters. If you're looking to continue with the PAA setup and add a hint of legitimacy, then AI + PAA sites are for you. And if you're not looking for PAAs at all, then go for the Pure AI sites - 1500 words of Pure AI Niche Relevant Content.