Top 3 for me are Flair, Vader, and Hogan.
 
If we're also counting when WCW was running the NWA and/or WCW International title as a separate world championship with the big gold belt in 1992-94, I'll include Barry Windham and Rick Rude.

Vader!
Remember when Vader first came out in that Gawd-Awful mask of his?  He'd take it off, put it down, walk away, turn around and point at it, and the horns would suddenly let loose with a powerful spurt of either steam or smoke under pressure.  Quite impressive!  Too bad no one today does that.

Rude held the WCW International World Title after WCW broke away from the NWA in '93.  
 
At the time the promotion was running separate WCW and NWA World Champions and planned to have Rude win the NWA title from Flair at Fall Brawl without NWA approval. Before some sort of compromise could be reached, WCW chose not to renew their membership. They kept the belt and had him beat Flair for what was just called the World Heavyweight Title after a lawsuit by the NWA.  
 
Sometime afterward they announced that it was no longer recognized as a World Title and merely called it the "Gold Belt" until explaining prior to the rematch at Halloween Havoc that it was a World Title afterall because the WCW International Board had come forward to say that they did in fact recognize it.

I'm sure everyone here has Flair as their Number 1. and rightfully so.  My second best is definitely Vader.  He was really booked well as the unstoppable monster and had such a dominant reign, though I did mark out when Ron Simmons won the World Title from him.

I'm a muta fan and I know he never had the world title in the states.
So, besides flair I would have to sat STEAMBOAT.
 
Vader and Sting (early 90s before the crow gimmick) also get a mention.

Hogan meant more than Sting, IMO, because Sting, even though he was WCW's "franchise", pretty much bombed as champion whenever they put the belt on him. Sting was always very popular, but he didn't really get "hot", in terms of helping the company make money, until they transformed him into the Crow and had him feud with Hogan and the nWo. In fact, WCW itself never turned a profit until about a year after Hogan came on board.
 
Btw, I don't think Windham or Rude were necessarily "greater" than Sting, but I did enjoy their runs with the NWA/WCW Int'l Championship, which was admittedly treated as a secondary World Title
 
Muta held the NWA World Title in 1993 for about a month and a half. He won it in Japan and lost it to Windham at WCW's SuperBrawl III. I believe he also came in as IWGP Champ and defended the title at Slamboree '95 against Paul Orndorff.
 
Dustin was U.S. Champ twice in 1993.
 
He first won the title after it was vacated when Rick Rude was stripped due to an injury at the beginning of the year. Rude eventually returned and they had a match in May on World Wide that ended in controversy. The title was held up as a result and Dustin eventually won it back after a few months. He would go onto lose it to Austin at Starrcade in December.
 

Ric Flair was the greatest world champion of all time. Vader would be 2nd and I would put Ron Simmons up there though alot of people would disagree.

Here is what I woud have to go with in this category. This is based on working ability, drawing fans to the matches, and making the title relevant to what was going on in the company at the time.
 
1. Ric Flair
2. Ricky Steamboat
3. Vader
4. Sting
5. Hulk Hogan
6. Bill Goldberg
7. Bret Hart
8. Dallas Page
9. Booker T
10. Barry Windham

People are seriously overstating pre-nWo Hogan's importance. He did nothing to turn the company around in his first run as champ, except job out the company's top heels (Flair and Vader) and have terrible JD Costello matches with his buddies Tenta and Ed BootyFace Zodiac Leslie that no one paid to see. Numbers didn't increase, nor did buyrates. Nada. WCW went to war when Nitro first aired, which was 15 months after Hogan had started his run there. And guess what? His act was stale as JD Costello. Fans were booing. The war didn't officially start until Hall showed up that fateful night. Hogan never drew JD Costello in comparison to what he was being paid until they turned him heel. They really had no where else to go with Hogan and thankfully Nash and Hall added about five years to Hogan's run up top.
 
Now Sting was not a huge draw, but that isn't his fault. When he put the company on his back, Flair had left the company, there were idiots or old purists like Watts holding the company back and financially that WCW wasn't near the financial waterfalls that poured out of ATM Eric post Hogan. Plus he was the only legitimate star the company had until Vader arrived. Hogan had a plethora of stars to job out, which got old fast, even as a heel. It's not fair to compare a man who was supposed to be a global star when the company was being run like a regional territory and another man who didn't do what he initially was supposed to because his act was stale and fortunately the "last resort" worked. Sting meant more to the pure, hardcore WCW fanbase than Hogan ever did. Hogan was the complete opposite to these fans as what Sting and Flair and guys like Windham   and Rhodes meant. Hogan himself was never proven a draw for WCW , the nWo was a draw by itself. Look what happened after the NWO disolved, hell, look what happened even before that. Look at the finger poke of doom. Look at the Hogan-Sting debacle. Who's fault was that may I ask you?

Flair and Sting would get my vote

easy
 
1. Ric Flair
2. Harley Race
3. Dusty Rhodes
4. Ricky Steamboat

I was trying to keep this list in the 1987 and beyond years because I did not want to bring up a topic in the wrong forum, but I since several posts mention NWA Champions in earlier times, I thought it would be okay to ask this question:  Does Race rank higher in most people's mind than Lou Thesz or Jack Brisco?  He does not in mine.  Granted, he won the belt more times than either, but I just do not see him as the classic performer of the caliber of Thesz, Brisco, Flair, Steamboat, and others.

It is an easy debate that everyone always makes very hard it it should be two lists the fist list is made up greatest wrestling champions that built and carried companies. The second is of greatest champions that had they all around wrestling skills.
 
List 1
1. Hulk Hogan
2. Ric Flair
3. Bruno Sammartino
4. Buddy Rogers
5. Dusty Rhodes
 
List 2
1. Ric Flair
2. Bruno Sammartino
3. Ricky Steamboat
4. Randy Savage
5. Sting