Kim 2007-to date
Yamaguchi 1991-1992 (or 1991-1997 extended to pros)
That said from 2007-2009 she was definitely a threat, and nearly won Worlds in 2008 (even if controversially so).
this year's nationals. And I disagree with your statement regarding Carolina and Caroline. I think there is no comparison between their situations. Carolina can very well win Worlds this year.
For her to win Worlds skating exactly as she has so far this season would require Kim, Ando, and probably even Asada to all bomb. It would require none of Czisny, Korpi, Lepisto (if at Worlds), or even Nagasu and Murakami to have a great competition. Now if she improves her skating alot from what she has shown in the international events this season then maybe she has a chance, but what she has shown this season despite some good placings would never win Worlds.
Yu Na has had Mao as her competitor for World and Olympic titles. By a lot of the accepted logic here, Ando, Rochette, and Kostner etc. have been good enough for silver and bronze. Only recently has Ando's fire re-emerged and that seems almost proportional to Mao's recent meltdowns.
Admitedly, my knowledge about skating beFore the 90s is not that great, but even thinking back to the time of Ito vs. Harding... we all know that didn't amount to much in terms of a head-to-head while both were dominant.
However in my opinion:
Zayak and Sumners were both major threats to Witt at the same time from 82-83. Chin and Ivanova were both major threats to Witt in 85-86. Thomas and Manley were both major threats to Witt from 86-88 (minus Manley in 86). So 84 was the only season Witt had only one main rival. Even Kadavy came quite close to winning Worlds in 87 over Witt and Thomas both at their best in 87 (not winning by others bombing like Butyrskaya or Hughes or even Arakawa).
Harding and Ito were both major threats to Yamaguchi in 91-92, and then after Yamaguchi turned pro Ito, Sato, and Biellmann were all main rivals to her. If it had not been for the figures Ito would have had no threats before 91 but because of figures she had major threats from Trenary and Leistner in 89 and Trenary and Lebedeva in 1990, as much as in free skating alone she made them look like novice ladies.
And Ando as not only a World Champion, but someone who beat Asada twice already at Worlds, and someone who has finished over Asada in quite a few events over the year (even if Kim not so many) and is arguably right now the favorite to win Worlds for a 2nd time this season, would have to be considered a 2nd major threat to both Kim and Asada over this period, in addition to each other. And maybe I was misinterpreting you but you seemed to think Kostner had been in years past as well.
It is hard to rate Kristi's competition that highly in a way I guess since Ito and Harding never skated anywhere near their potential in the big World events those 2 years, and the rest including Kerrigan werent very good yet. The 91 Worlds and 92 Olympics were potentially amazing competitions, probably should have been the best of all time if all 3 had skated their best, which never panned out to be.
Guys, all this talk about Carolina not having a shot. Lepisto with all her doubles beat Ando who had a nice clean FS at Worlds last year. The judges like to have at least one European lady up their in the standings. I'd say Caro is a contender even with her loops and sals, the other ladies can afford more mistakes than she can, sure, but if Caro goes clean with the layout she's been doing so far this season, she will score well and could very easily medal.
Ando bombed the short at last years Worlds with 2 falls which is the only reason she lost to Lepisto at last years Worlds (which people who cried about the result continually forget). The only one who did 2 clean or almost clean performances with all triples was Phaneuf who lost the medal (barely) since she is a no name on the World level.
I could see Kostner getting a bronze at Worlds this year maybe. However others are talking about her winning with her current jump content and there is no way that is happening unless we have the worst skated event ever.
If they need a European lady up there who is to say it will be Kostner. If Korpi skates well and wins Europeans I would say she is the one who will get the most backing at Worlds. She is skating more consistently this year, the judges like her skating as well, and she is atleast doing/trying all the triples.
THE BEST in the world I believe. I think the judges see her that way too, if only she would skate consistently clean.Her speed and edges are one of the best though.
She can be World champ if she skates the way she is capable of and I will be clapping and cheering happily for her if she does it!