What size is your room? What's your budget? Do you have a preference in terms of connections (speaker/RCA/XLR)? Music only or music + movies? Any placement / WAF issues?
Ported subs can be as good in a music only system, but my first choice would be a sealed sub(s) for music. Rythmik's servo controlled subs are great for music. Without knowing more it's hard to say which one would be best. I have two SVS SB13 Ultra subs in my main music system and am very happy with those and wouldn't hesitate to recommend SVS. I have two Rythmik F25 subs that I use for home theater. I would use those (or maybe just one) for music, but I can't due to space/placement issues in my room. They are too big to fit where I would want them for music.