I'll try and bite my tongue on some of these organizations. I haven't competed in a while, but when you have so called 'open' point-karate tournaments, things can get pretty damn sloppy. I'm not so fond of the NBL. Not saying it's not fun and there aren't some great fighters, but because there is no 'format' that registers contact, you'll have the craziest stuff be thrown at you. Some of us at our dojo (BACK IN THE DAY... why do I feel old in my mid 20s?) would occasionally go to some NBL events and clean house, but you could lose by some of the stupidest things, the lightest of touches with no form required. Some people walk forward throwing round house kicks without bringing their legs down because if they tapped you with that, they'd get a point. I'd love throwing jumping Uraken Uchi's, they worked every time (if you didn't get points deducted for overly aggressive contact).
There was one I liked, I think it was the WKA. Still very sloppy, but you had to actually make some contact to score a point, and some of those guys would knock you on your ass.
I mainly competed in the classical Okinawan tournament circuits, namely the JKA and the WKF (JKA WF-US and USANKF for American branches). First off, the sense of timing, footwork and distance are just so superior, it's unquestionable. Second, there's a format to how you register a strike-- things are rarely ever sloppy. Third, it still feels VERY traditional, unlike some of these other open tournaments where guys fight in sweats or in warmups or modified, crazy Ryu-esque gis.
Not to say both organizations don't have issues.
To score, you have to show the judges proper 'form' so after you strike, your stance and body is so god damn exaggerated... not to mention you have to stop fighting; in other words, you both strike, freeze up, and then listen to see if the judges thought you did something to deserve a stoppage. Listen too long and the other guy is going to sweep you on your ass.
Both (especially the WKF) are struggling to figure out how to deal with standup grappling and the rules are always changing (too little and you're negating all the great throws of Karate... too much and it can turn into a judo match!).
Both (especially the JKA) struggle with arbitrary contact. In one match, I'll get bashed in the face with a punch and my opponent will get the points. The next match, I hit my opponent the same way in the face and I get a penalty-- it's all about how the judges feel.
And obviously the other big problem is, if you don't do traditional Okinawan karate, you're not going to do well because the techniques are focused around the Okinawan Karates, and mostly for arts like Shotokan, Wado, and Shito (though Goju-Ryu does compete and do well, and some Kyokushin guys even compete just for the footwork and timing).
I still love both, and I do miss the competition.
USANKF/WKF competition:
JKA US: