I'll venture here. My take on female vocalists is a bit different because it is about the music they write and sing and not necessarily if they are considered great vocal talents.
Molly Rankin (Alvvays)
The Raincoats
Deborah Iyall (Romeo Void)
PJ Harvey
Aimee Mann
Cherry Glazerr
Sad13 (solo and Speedy Ortiz)
Courtney Barnett
Elizabeth Frasier (Cocteau Twins)
Kerry Alexander (Bad Bad Hats)
Victoria Legrand (Beach House)
Lyn Byrd (Comateens)
Patti Smith
Sonya Madan (Echobelly)
Marijne van der Vlugt (Salad)
Justine Frischmann (Elastica)
Mary Timony (solo and several bands, currently Ex Hex)
Corin Tucker (Sleater Kinney)
Shirley Manson (Garbage)
Marissa Paternoster (Screaming Females)
Phoebe Bridgers
Julien Baker
Lucy Dacus
Michelle Zauner (Japanese Breakfast)
Julia Jacklin
Juliana Hatfield
Kate Bush
Joni Mitchell
Alison Mosshart (The Kills)
Lene Lovich
Nina Hagen
Jill Cunniff (Luscious Jackson)
Miki Berenyi (Lush)
MIYNT (don't know the singer/songwriter's name)
Pip Blom
Kay Hanley (Letters to Cleo)
Hope Sandoval (Mazzy Star)
Ambrosia Parsley (Shivaree)
Siouxsie Sioux
Annie Clark (St. Vincent)
Suzanne Vega
Tori Amos
Tristen (Tristen Gaspadarek)
Kristin Hersh (Solo and Throwing Muses)
Tonya Donnelly (Throwing Muses and Belly)
Ellie Rowsell (Wolf Alice)
Jenn Wasner (Wye Oak)
Alison Moyet (Yazoo)
Karen O (Yeah Yeah Yeahs)
Exene Cervenka (X)
Bjork
Fiona Apple
Liz Phair
Annie Lennox
Adrianne Lenker (Big Thief)
Margaret Glaspy
I guess that's enough even though there are a ton more.
Most underrated female recording artists..
I'm always looking for female singers who make my 2 channel system seem worthwhile for all l have spent...the list includes Nora Jones, Diana Krall , Sade and many others.... there are some fabulous singers out there but not recorded very well...lm adding Bonnie Raitt to my top list..The Bonnie Raitt collection red book cd...tracks 16 and 17 are spectacular on my system... I'f anyone could add a suggestion it would be appreciated..