To Nicole: Avril sort of spearheaded the "singer-songwriter" movement of 2002 with Michelle Branch and Vanessa Carlton right behind her. She was a pioneer of her own.
Unforunately, Aretha didn't have huge commercial success in the '90s other than a few R&B hits (most notably the glorious "A Rose Is Still A Rose"). The reason why Aretha, Tina, Debbie Harry were left out were because VH1 thought their prime was in the '60s-'80s.
Realistically, Aretha would be an automatic top 3 (#2).
That whole singer-songwriter "movement" (was it really a movement? Nothing really came of it. I'd say it was more of a twitch) was the result of the anti-Britney sentiment more than anything else.
I never take these lists that seriously. I always enjoy them though just because I think they're fun and harmless. There are definitely some odd placements. I bet VH1 feels pretty stupid having Whitney at number 6 though.
I do have to say this though: Fantasia at #32? WTF? Admittedly, I have an irrational hate for Fantasia, but no way she deserves to be that high, right?
I'd also say that Cher and Celine deserve a spot in the top 10, along with Britney. I'd take out Adele, Gaga, and Pink.
Trust me, that's not even stanning. I remember many covers and articles talking about "the anti-pop movement" of 2002. They always referenced Avril, Michelle, P!nk and mentioned how even the pop artists went in a more urban direction (remember N'SYNC''s "Girlfriend" with Nelly?)
The original one only needed a few changes and it would have been perfect:
10. Beyonce/Janet
9. The Supremes
8. Billie Holiday
7. Annie Lennox
6. Carole King
5. Joni Mitchell
4. Janis Joplin
3. Tina Turner
2. Aretha Franklin
1. Madonna
It is for the last 20 years only. Your list looks like an all time list and in that case I think Aretha should be #1 and Barbara needs to appear in the top 10.
@ Bey being #3. Loves it. That outs the way, there are SO many flaws. 
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