OK, this is important:
1). How much power are you willing to have, or plan to have?
2). One or two subs?
With 1000w total for two subs, you should look into something like DCONs...
or one SA 12/GCON/Type R
Not so with the W6s. 1000 - 1200 should push those those just fine. Most stock alternators can handle this with a good AGM battery and Big 3 upgrade. This will still be quite a bit of bass. You will actually save a lot of money going this route. These can be ported no problem, but need to be tuned really low. That's exactly what I would do personally if I were to be presented with a query of SA-12s vs. W6 12s..
yeahh i really dont want to buy another alternator cause i just bought a brand new one haha nothing special. but i dont care about making people tap out i just want something that has really good SQ and doesn't distort when i turn it up but i also want something you can feel in your chest. But about the tuning, Jls website says to tune the box to 32Hz. Is that low enough?
Not sure if it was mentioned but OP what music do you listen to? So we have an idea of what your verison of SQ is...