Its hard to compare them since they all brought something different.
Elizabeth was probably the greatest female manager in WWF history. Sable was the definitive sex symbol for the WWF and ushered in that whole era of women, and Rousey was a legit fighter that made the transition to wrestling and brought a level of credibility to her in ring presence.
Miss Elizabeth was the only real female star during her time. Wendy Richter had her falling out with the company, and Women's Wrestling was all but forgotten by 88-89 in the WWF. But Elizabeth was a manager and was attached to one of the biggest stars, The Macho Man, so that allowed her to be a constant presence on TV, and for the little that she did, she worked beautifully. I mean her story with Savage is arguably the greatest love story ever told in wrestling history, and she was vital to the success of The Mega Powers' storyline (both the rise and the fall), and to this day, I still say that is one of the top two best storylines in company history (the other being Austin Vs. McMahon).
Personally, I think she deserves to go into the WWE Hall of Fame, even if she wasn't a physical presence on the show. Again, she was there to be a manager, and she offered emotional investment, sympathy, and a compassionate presence on a show full of roided up and intense muscle heads. Compared to other managers, she also offered something different from the likes of Bobby Heenan, Slick, Jimmy Hart, Paul E Dangerously, Jim Cornette, and the rest, and it wasn't purely sex appeal either. She was an important component for storylines and she made Randy Savage better by being attached to him.
However, her contributions were entirely as a manager and not a wrestler, so it is really hard to compare her to Sable and Rousey in that regard.
Sable transitioned from an Elizabeth type, to a wrestler, and her popularity helped to bring back the dormant Women's Championship. She brought an over the top sex appeal that was common at the time, and broke new ground by being in Playboy and things of that nature. However, I don't look back on her as fondly as I do Elizabeth. Where I can point to storylines and moments that Liz had that were vital to my enjoyment of the show, Sable didn't really have that. Aside from her story with Mero to get her into the action, there wasn't really that much. They sold her as a wrestler, but she was NOT good at it. At best, you'd get a good mixed match out of her, but watching her go one on one with another woman is downright miserable. Also, her promos were terrible. Liz wasn't great on the mic either, but she also didn't talk much and said more with her actions and facial expressions, but Sable was coming up at the time when everybody was expected to talk, and her voice was like nails on a chalkboard. I give her credit for being as over as she was and being used to start up the women's division again, but she was a sex symbol that they tried to convince me was more than that, and I couldn't buy it. To me, Trish Stratus was better at being both a sex symbol and a wrestler, and sold herself well at being both. And even the other sex symbol types that were there at the same time as Sable like Terri Runnells and Sunny were better managers that talked better, did more, and could elicit some emotional responses from me.
Now Rousey brought credibility as a fighter. Her career in MMA and Judo gave her instant cred, similar to how guys like Kurt Angle and Brock Lesnar had instant cred when they came in. However, success in real fighting and real sports doesn't always equate to a smooth transition into a work. Does anybody remember Sylvester Turkay? Or how about Daniel Puder? Fortunately, Rousey did mostly really well in her matches, bringing intensity and believability. The biggest issue with her were her promos, which were just awful. I felt she was a type that didn't need to talk as she was believably bad ass on her own, but what do I know? But hey, more than anything else, it was her legitimacy and name recognition that allowed for the first all women WrestleMania main event. Yes Becky got over, but I think they were leaning towards Charlotte Vs. Rousey as the closer before that happened. I think Rousey's involvement made it possible for that to happen, and she deserves credit for that.