The Rock is one of the greatest of all-time for sure (both in WWE history, and overall pro wrestling history), but he's not the greatest (again in both WWE and especially overall pro wrestling history).
The Rock's greatest shortcoming when it comes to his legacy, is his lack of longevity. I know many would say that Austin's run as a top guy was just as short, but Austin had about a decade in the business as one of the top workers in the business to support his status as an all-time great. The Rock started training in 1996, debuted the same year, floundered his first two years (due to bad direction and booking), got over big in 1998, was an absolute top name from 1999-2001, went part time in 2002 and 2003, and then left for good other than brief nostalgia runs in 2012 and 2013.
Austin and Cena, and especially people like Hogan, Flair, Andre, Bruno, Taker, HBK, Hart, Savage, Piper, etc far surpass the Rock when it comes to longevity. Taker, HBK, Hart, and Flair, as well as Cena weren't as big of draws and reached the mainstream of pop culture like the Rock was able to do, during his wrestling career alone. Cena has come somewhat close in recent times as his wrestling career is winding down, but Cena at this point, which is probably the most famous outside of wrestling that he's ever been, wasn't ever as red hot as The Rock was in the late 90's/early 00's. People forget, but Austin also during that time was red hot too and was appearing on TV shows and talk shows during his run in the late 90's.
As was highlighted in the Bruno documentary, Bruno was a pretty big celebrity in the 1960's, for that time. Being a celebrity in the 1950's and 1960's wasn't near as big like it is today, and thus Bruno unfairly gets looked at as not being near as big of an overall star like Hogan, Rock, Austin, Cena, and even Andre. But I didn't see any of those wrestlers having private meetings with the Pope. Bruno was pretty damn huge for his time.
Andre though was the one that really broke through as a pop culture icon (other than Gorgeous George in the 1950's) beyond wrestling.
Hogan of course took it even further in the 1980's, and to this day is still probably the one wrestler that everyone who's not a fan of wrestling can name (or The Rock).
Flair had so much longevity as one of the greatest performers in the business. He was easily in the top 5 workers in all of wrestling for about a 20 year period (1975-1995). That's pretty darn impressive. Probably only Shawn Michaels could match that when it comes to modern wrestlers (Bret Hart could've had his career not been cut short).
I'm kind of going on a bit of tangents so I apologize for my posting being so unorganized lol.
If I was to rank the top 10 stars in the history of WWE it would look like this....
10. John Cena
9. Macho Man Randy Savage
8. The Undertaker
7. Shawn Michaels
6. Bret Hart
5. The Rock
4. Andre the Giant
3. Bruno Sammartino
2. Stone Cold Steve Austin
1. Hulk Hogan
Cena I rank at No. 10 because he wasn't as good an in-ring performer (IMO as Austin, Savage, Hart, Michaels, Taker, and the Rock. He was a better in-ring performer than Andre, Hogan, and Bruno, but he was not near the draw or as impactful on WWE and wrestling as a whole (especially) as those guys. But he was the definitive figure of WWE in the post-Austin and Rock era, and his longevity and improvement throughout his career (similar to the Undertaker), makes him one of the best ever. And though he wasn't as big a draw as Hogan, Rock, and Austin, at their peaks, he was a stable presence for WWE for almost two decades, and stable enough to allow for WWE to become an even bigger company in the global market. He's definitely an important figure in WWE history for sure. But to me he falls short as an overall wrestler compared to the other 9 guys on this list.
Macho Man I rank at No. 9 because he was a better in-ring performer than Cena and was more influential on future wrestlers, but didn't have the longevity and consistency in WWE as HBK, Hart, Taker, Andre, and Bruno, and wasn't as big a star as Andre, Hogan, Austin, Rock, and Bruno.
The Undertaker I rank at No. 8 because he had the most consistency and longevity of everyone in the top 10, revolutionized how to work in wrestling as a big man (he's the second greatest giant/big man wrestler in history behind Andre), had the greatest gimmick/character in the history of pro-wrestling, but wasn't as great an in-ring worker as HBK, Hart, and Austin, and didn't reach the mainstream of pop culture like Bruno, Andre, Hogan, Austin, and Rock did.
Shawn Michaels I rank at No. 7, because he's arguably the greatest in-ring performer in the modern history of pro wrestling in America, and was a cornerstone of WWE for almost 20 years. He was a better in-ring performer than Bruno, Hogan, Andre Rock, Cena, Taker, and Macho Man (though that's closer), but is slightly behind Hart (IMO), and like Taker, never reached the mainstream of pop culture like Rock, Hogan, Andre, Bruno, and even Cena. He also was probably the weakest draw of everyone in the top 10.
Bret Hart I rank at No. 6, because IMO he was the greatest in-ring worker of everyone in the top 10 (just slightly ahead of HBK), revolutionized the style of wrestling and workrate in WWE helping to lead the way for smaller, better athletes to be top guys in the company (even when Vince Sr. ran the company in the 60's and 70's, he favored bigger, charismatic stars rather than great in-ring performers like the NWA did). There would be no current era of Punk, Bryan, Rollins, Styles, etc. as top guys, or even the early 00's period of Angle, Guerrero, Benoit, Mysterio, and Jericho, without Bret Hart paving the way from 1992-1994. Bret also really showed that WWE could draw big across the world outside of America, where he was by far the top star and draw for WWE. Though WWE was touring outside of America in the 80's during the Hogan period, it was during Hart's reign at the top in the early to mid 90's that WWE really started heavily touring outside of America which paved the way for WWE becoming a global company. Bret Hart really was one of the most important wrestlers in WWE history, and doesn't really get as much credit for that as he should. That being said, he was not as big a star or draw in America as Andre, Bruno, Hogan, Rock, or Austin, so he falls short to them.
I rank the Rock at No. 5 as he was the second best wrestler in the history of pro wrestling on the mic (only behind Ric Flair), was a very solid in-ring performer, was probably the fourth biggest draw in WWE history (behind Hogan, Bruno, and Austin). He was a great all-around talent. His lack of longevity though hurts him and thus he falls behind earlier stars like Andre, Bruno, and Hogan who had far more longevity and impact on the business, and he was never quite at Austin's level as the top guy. You can argue that he was more liked by the fans and maybe even drew more at certain points, but the reality is that Austin was always pushed as the top guy over the Rock when both guys were active at the same time. The best example of that is Austin beating the Rock at Wrestlemania X-7. At that point many feel the Rock had surpassed Austin, but if WWE truly felt that way, they would've had the Rock win, which they didn't. They went with Austin. The Rock finally beat Austin, when Austin retired. That should tell you right there that in WWE's eyes Austin was always the top guy over the Rock.
I rank Andre the Giant at No. 4 for revolutionizing what it was like to be a giant in pro wrestling (which the Undertaker would take further in the 1990's), being one of the most unique attractions in the history of the business, becoming a mainstream pop culture icon outside of pro wrestling which really helped lead to the wrestling boom of the 1980's and for his longevity as a top name. Andre may not have been the in-ring performer that Savage, Taker, HBK, Hart, Rock and even Cena were, but he was a bigger star/draw than all of them and was more important to the history of wrestling than all of them. Andre falls short of Bruno, because he was an attraction, whereas Bruno was the era-defining figure of his time, as were Austin (who was also a better in-ring performer and talker), and of course Hogan who in many ways took what Andre did in the 70's to the next level in the 1980's.
Bruno ranks at No. 3 because he was the man that literally made WWE a vital wrestling company, has the longest reign with a world title in the history of pro wrestling, (which speaks to his drawing power and popularity), as well as his drawing power/popularity, and longevity. Bruno at the twilight of his career in the mid-to-late 80's was outdrawing Hulk Hogan in some cities and shows. That's remarkable. That being said, he wasn't as good an in-ring performer as Austin was, and he didn't change the wrestling business as a whole the way Hogan did, though he's still among the 10 most important wrestlers in the entire history of the business.
Austin ranks at No. 2 for being one of the best in-ring performers of the 1990's (both his time in WCW and WWE), revolutionizing the face/heel dynamic in pro wrestling (yes there were tweeners before him like the Road Warriors and Dick the Bruiser, but Austin took it to another level), literally saving the WWE from declining majorly, beings one of the greatest draws in the history of pro wrestling, even though it was shorter compared to other bigger draws. Austin, was in many ways the total package of what a pro wrestler should be. He was charismatic, had a great character, could cut amazing promos, was a great in-ring performer and worker, had great in-ring psychology, was believable in the ring and in his promos, was a major draw, and reached the mainstream of pop culture. There were certain areas that other wrestlers were better at, but when it comes to all aspects that makes a wrestler great, he's as close to the total package as anyone. But his impact on WWE and the wrestling industry as a whole wasn't quite as big as the No. 1 guy.
Hulk Hogan ranks as No. 1 because he really brought pro wrestling and WWE to the mainstream, and forever changed the wrestling business. The modern era of pro wrestling exists thanks to Hulk Hogan, his starpower, drawing ability, (along with Vince McMahon and his vision as a promoter and booker, but we're talking just wrestlers here). Hogan wasn't the in-ring worker that really everyone else in the top 10 was (Andre in his prime was a beast for a guy his size), but when it came to crowd psychology, perhaps none of them were better than Hogan. Hogan also helped spawn two boom periods of pro wrestling, which no one else on this list, or maybe even anyone in the history of American pro wrestling was able to do. That shows how impactful and big of a star as he was. What Elvis Presley was to rock and roll, Hulk Hogan was to pro wrestling, the face and ambassador, and biggest star, even 30 years later. Bruno helped WWE become a relevant pro wrestling company, Hulk Hogan helped make it the dominant and definitive pro wrestling company.