Which size and which sub?

[Ren Brower]

I'm looking for hard hitting bass. Ideally I want something that will shake the doors. So should I get 4 8s or 2 shallow 12s? The 8s would be front firing and the 12s would be down firing. At first I see the sundown sa-8 v3 and the b2 XM8 which weigh me to the 4 8s side but idk much about the shallow 12s.