I don't put Missy in the ranks of a Mia X, Eve, Brat, Rage or a Gangsta Boo or even Kim and Foxy. Mia, Eve, and Rage are all women I consider lyricists. Brat too. Kim and Foxy would be in that bracket, but they had writers. Then you have the pioneers like MC Lyte, Latifah, and Shante.
What Missy brought to the table was unique and the only comparison is really Lauryn Hill, except Lauryn is a lyricist. Both are what I consider full fledged Hip Hop artists. They rap, sing, write, and produce. Two of the best artists Hip Hop ever produced, male or female. Of course Missy had Timbaland and Lauryn had the New Ark kids, Che Vicious, and James Poyser.