JL is pretty decent. But its way too expensive. The only thing they make that I really care about is the W7.
As far as the size of subs go, you cant really base anything off of that. You can make 10s sound just as good as anything else. I had 1 12 in my car that would dog walk the doo dee out of just about anything on the street. And my home boy had 1 8 in his accord that was loud as crap. You just have to have the right setup. The most important thing is having a good amp, not having one that says "1200 max" or w/e and really does like 120 rms, lol.