@ everyone ignoring Shania Twain

Y'all so obsessed with numbers, you'd think these stats would convince most people:
ONLY female to have three diamond albums in the US
Biggest selling album by a solo female artist of all time w/ approximately 40 million sales worldwide (does The Bodyguard count?).
Hits like Man! I Feel Like A Woman, You're Still The One and That Don't Impress Me Much are testimony to the fact that one doesn't need a great position in the charts to make classics.

Pop music isn't one specific genre, it's whatever's popular at that time. And Shania definitely became a pop girl by 1998 as a result of pushing so many albums and increasingly becoming a familiar name in the media. She was inescapable.

In any case, she's definitely "above" Rihanna, Lady Gaga and Adele in terms of success. These girls are relatively new to the game, especially compared to someone like Shania. So, I'm hesitant of including said girls on the list. Like, in 1996, everybody would be naming Alanis Morissette amongst the top five and in 2003 Norah Jones.

Right. The Bodyguard Soundtrack sold a lot because of the movie though, whereas Come On Over is a product of Shania's celebrity and music alone. And it's not like The Bodyguard outsold it by that much. But I agree, second best selling.

Her Come On Over Tour grossed ~$80 million and Up! Tour more than $100 million. These numbers seem small compared to someone like Madonna, but she's above a lot of the other girls. She's doing a successful residency in LV right now.

I just fail to see the relevance of films as far as pop careers are concerned. Like, one cannot credit Whitney for ALL of the success of The Bodyguard. Costner probably had a say too. For this reason, I find movies to be an uncertain confirmation of a pop star's power and relevance in the public. I think her sales say enough about that. (Not taking anything from Whitney's success, however).

Well, Shania did contribute to making country music "cool" again, alongside Garth Brooks. The scene in country music had, apparently, been basically lifeless for years. She's also become the prototype for the fine line between pop and country, securing success on both formats. Although this can be traced back to the 80s, it was with Shania that it really became a thing. Basically all of the pop-country girls to come post-1995 have been marketed with Shania as the standard. 2009-Taylor is a blatant copy Dixie Chicks and Rascal Flatts are doing the same.

Shania is basically a pop singer who adds a banjo and twang in her songs every now and then. By your logic, Mariah is not a pop girl, but an R&B act.
I agree that during her first two eras, she was more a country singer, but from her third album she's been a pop girl just like Taylor is a pop girl today.