Well, a sealed box is easier to build that I can tell you, while a ported box requires more calculations so you get the right box tuning, and such, but you will get much better results with a ported box cause I've heard metal in sealed box, and it just sounds weird, like somebody put a pillow inside the bass drum to block the port kinda sound.
I have a friend who listens to same type of music you do along with industrial, and he has 2 w7 12's in a sealed built to JL's specs, and he played metal on it, and it sounded so weird compared to me listening to actual shows I went to since I have a bunch of friends who are in local "Hardcore" bands, and they go nuts with bass drums, and when I hear that sound being reproduced on a sealed box, it sounds like it's missing that bass drum port sound I look for.
But you are in the right place, cause if you can't figure out a ported box, there's people here you can pay to design one for you one, like RAMDesigns, 412CVX, and a few others.