Originally Posted by
Huntsman Spider
I would consider Black Widow in her current and last run more of an anti-hero. She's largely trying to atone for the crimes and misdeeds of her past, and the revelation of said crimes and misdeeds to the whole world has put her on the outs with the Avengers and S.H.I.E.L.D. She's nowadays more of a lone wolf trying to survive and stay one step ahead of both enemies and former allies alike long enough to clean up all the red on her ledger, so to speak. If that's not an anti-hero, at least not in the context of the modern Marvel Universe, I don't know what is.
I do like your list, though I would mention that Red Sonja no longer belongs to Marvel Comics; the character is now with Dynamite Entertainment. Valkyrie having her own comic series would be excellent, especially for the potential to expand the world of Asgard and Thor with a different perspective now that Loki's title has concluded, and she could easily interact with both Thor Odinson and Thor Jane Foster. Thundra is a character I'm somewhat fond of as well, though mostly because at least one version of her has a genetically engineered daughter with the Hulk's DNA named Lyra, a.k.a. the All-New Savage She-Hulk, that I'm deeply fascinated with. Given the beating feminism as a concept and an ideology has taken in recent years, a Thundra title would be good for exploring that issue in a more modern context, since Thundra was initially written as more of a misandrist than an actual feminist, being literally at war with men.
With Tigra, they could give her a costume that still covers the minimum necessary for the sake of not overheating her, but looks more like something a professional athlete would wear as opposed to a bikini model. Satana would definitely be a great hook into the supernatural arena that's finally starting to get explored again with Doctor Strange's books, Howling Commandos of S.H.I.E.L.D. (R.I.P.), Scarlet Witch, and the upcoming Ghost Rider title featuring Robbie Reyes, and a team-up with Magik of the X-Men or the Scarlet Witch wouldn't hurt, either. As for Spider-Woman, it wouldn't be too hard to combine both of her costumes into an outfit that works for everyone, and with Mattie Franklin coming back in Dead No More (clone or not) and Web Warriors' conclusion, it'd be a great time for Jessica, Julia, and Mattie to join forces again (with Anya Corazon and Cindy Moon/Silk thrown in) and maybe have an ongoing team-up title like Spider-Man and Deadpool have.