Oh man, this is TOUGH. Great thread, though. Let's see here, how to divide this up? Ah yes! Tournament Style!
Round One
Rule #1 - TNA World Title > ECW World Title.
I base this off of the fact that, despite the ratings of ECW being essentially equal to that of TNA, the fact is that TNA is an entire promotion, whereas ECW is the 3rd tier on an already depleted and split roster from WWE. Also, though more subjective, it's fairly easy to argue that the level of talent competing for the TNA Title is greater that that of the ECW Title. It's hard for anyone to take Mark Henry, Matt Hardy, and Shelton Benjamin over Kurt Angle, AJ Styles, and Christian Cage.
Rule #2 - WWE Intercontinental Title > WWE US Title
Both championships have been disrespected as mid-card titles the past year and a half or so, and I'll even accept that fact that, in my thread from a few months back that had the US title voted OVER the IC title by a 81-80 margin. But that notwithstanding, the Intercontinental Title can enjoy the fact that it is a) on the top brand, and b) has history on its side. When WWE won the war against WCW, the US Title lost alot of its historical luster. The IC Title did not. When I think of the IC belt, it still invokes thoughts of Bret Hart, Shawn Michaels, Mr. Perfect, Razor Ramon, etc.
Rule #3 - IWGP Title > AJPW Title
The IWGP Title has more prestige and history to it. The Triple Crown belt is great, but the IWGP edges it out just a touch. Some absolute legends have held the IWGP, such as Big Van Vader, Antonio Inoki, Bam Bam Bigelow, Scott Norton, etc.
Rule #4 - ROH World Title > NWA World Title
Oh how the mighty have fallen. It's not the 80s anymore. Between Shane Douglas tossing down the NWA Belt to start Extreme Championship Wrestling, to TNA separating, etc - there hardly is an NWA Title anymore. ROH is up and coming, and the belt itself has created a name for itself as a launching pad for Samoa Joe, AJ Styles, CM Punk, etc.
Ok, round two.
Rule # 5 - TNA World Title > IWGP Title
It pains me to say this, but the TNA World Title is defended in the US, the IWGP title is defended in Japan. That makes the TNA World Title more relevant in the West, which is what I am going by. The IWGP Title has more worldwide influence, but the TNA World Title has more mainstream attention.
Rule #6 - WWE Intercontinental Title > ROH World Title
ROH is a #3 promotion at best. It's trying to carve a niche as a wrestling experience, and that's fine. But it has little exposure, and the stars who come out of there don't always live up to the hype. Such a small niche audience pays any attention to the ROH Title anyway, but the IC title is well known and has history.
Final
Rule #7 - TNA World Title > WWE IC Title
This is strictly due to the disrespect the IC Title has seen for the past 2-3 years. Aisde from Johnny Nitro, there has not been a true, regular, meaningful IC Title reign. The TNA Title set out to set itself apart from the NWA Title, and I think putting the belt on Kurt Angle first and foremost was a smart way to go with it. It'll be interesting to see if my answer to this stays the same in 6 months, with the IC Title and Kofi Kingston getting a legit push and the TNA Title on Samoa Joe losing steam.
But for now, the TNA World Title is my answer.