Io Shirai is literally female Tanahashi. It's not even a joke, that's her whole thing. But while Tanahashi has better adapted in recent years and knows how to play up an audience, Io is just kind of basic and leeches onto anyone popular to maintain her spot.
Kairi Hojo, Ayako Hamada, Meiko, Natsuki Taiyo(retired), Arisa Nakajima, Syuri, Hikaru Shida, Kimura are all wrestlers I'd put over Io. and that's not counting the gaijins like Starfire.
If you want to get joshi and understand its popularity, you want to watch the old shit. The old shit is just as good as any mens wrestling of that era and they've never been able to compete with it since. Crush Girls, Dump Matsumoto, Dynamite Kansai, Devil Masami, Bull Nakano, Aja Kong, etc. It'll never replicate that wild fandom it had then