I know it is just "the nature of the beast" with some members, but I just don't understand all of the arguing over what is better. You want to know what is the best sub in the world? The one that sounds best to you, works in your room (sound/size/shape), fits your criteria, company provides good customer service and is priced accordingly. Guys, we all like different stuff. Brunette, blonde, red head / Android , Apple / Ford, Chevy, Dodge / American, European, Japanese / so on and so on. Just because someone has a different sub than you doesn't make them your enemy.
Ironically, most of the members on here that I relate to the best and respect their opinion the most, have different subs than I do. The horror! There are A LOT of knowledgeable members here that share their knowledge and experience with the rest of us. I'm not saying you can't disagree with someone, but the way you do so can be handled multiple ways.
Personally, I have never had the pleasure of hearing the current stuff from PSA or Rythmik, but I know they both make very good products. I have heard/read very good things about Enrico and have dealt with Tom personally and received excellent customer service from him long before I ever bought (SVS) subs from him and years after as well. I don't own PSA subs either.
So many variables....I think Imureh's experience goes to show it is very dependent on your room/personal taste. He heard a JTR sub at a friends house and liked it, but didn't like it in his room. The Rythmik sounded better for him. Unfortunately, that really is the only true way to make sure you pick the best option, is to demo them in your room. You "usually" have to eat a return shipping cost, but it's cheap peace of mind knowing you picked the right one.