What materials to use? Substance? PBR? Other?

What material type is the best to use in what instance?

I am currently using Substance materials but they increase my texture streaming pool by quite a lot, would it be better to use PBR materials or something else?

Those aren’t separate things, Substance materials are PBR as well. Substance gives you the ability to modify textures at runtime, it has some procedural settings that change the texture and then it rasterizes it so that is probably what causes a higher performance cost.