Past and present? UFC is obviously the most prestigious currently and at one point PRIDE could claim that too. WEC belts were legit in the lower weight classes. Strikeforce and Bellator were / are big enough and international enough that I would call there champs world champions. Any other orgs you can think of?
AK-BJJ - Past and present? UFC is obviously the most prestigious currently and at one point PRIDE could claim that too. WEC belts were legit in the lower weight classes. Strikeforce and Bellator were / are big enough and international enough that I would call there champs world champions. Any other orgs you can think of?
Fucking 02ers...
What the hell kinda responses are those?
AK-BJJ - What the hell kinda responses are those?Typical UG responses. The douches come in numbers
Dream
Bodog had a ton of top guys in it.
Affliction
Are we just talking mma? Cause UFC is the only org you can legit say "world" champ.
Past, I would go with Shooto.
Invicta
UFC and Pride would be it. Bellator isn't there yet and I'm not sure Elite XC or Strikeforce ever were either. Strikeforce and WEC are borderline though and could probably have an argument made for them.
Affliction probably could have been if they lasted longer. 
Not MMA but Glory
Ufc is the current gold standard for everything mma. If your a ufc champ you are a world champion.
Wec was like that for the lighter weight classes back in the day, and of course ufc/pride a few years ago
Everything else was second tier Junior tittles
Thats not to say the fighters in those orginazations where second tier. Some where elite world class but the title they would fight for itself wasnt.
Strikeforce ww title imo.
NBA, MLB, NFL, WC, WIMBELDON, PGA, PRIDE NEVER DIE FC
Jewels a couple years back maybe.
UFC
Invicta for the ladies
Thats it currently.
Gojira Ninja - Shooto, maybe. Probably.
No to Affliction, Bodog, IFL, EliteXC, dream, Yamma, Bamma, Whamma-Lamma ding dong
UFC, Pride, WEC, Strikeforce, Bellator. That's about it.
This is kinda how I think as well except for Shooto... But admittedly maybe I just didn't follow it close enough. After watching WSOF this weekend theirs might mean something if they can stick around too... Like at a Strikeforce level.
UFC, Pride, Shooto, and ZUffa era WEC are the four that I would consider.