Recently, many people have been getting behind the #wewantwidow campaign. Most cite the need for strong, female hero-led movies. This is all well and good, except for the fact that the Black Widow is, and always has been, written as a great supporting character. This isn't necessarily a bad thing, but it is also clear that female heroes aren't getting their dues at the box office. The Captain Marvel (Carol Danvers) movie is a good start, but there are other heroines that deserve their time in the spot light.
The Scarlet Witch
Wanda Maximoff has already made her debut in the MCU, and a stunning one at that. Elizabeth Olsen did a fantastic job portraying the Sokovian heroine, giving her a powerful flair and fluidity in both speech and action. More than any other introduced female character, she could carry a movie, likely with the Vision as her backup. In the comics, she's had many brushes with insanity, and with powers like hers, this makes her one of the most dangerous - and powerful - people on the planet. Scarlet Witch could also make for one hell of a movie.
Though Black Bolt is the silent king of the Inhumans, his wife, Medusa, makes up for that. A strong and powerful leader in her own right, Medusa has recently taken full leadership of the Inhuman City of Attilan, and makes it her personal responsibility to track down, meet, and train new Inhumans. Medusa could easily take the lead in an Inhumans movie, even over Black Bolt. Plus, her prehensile red hair could be used in some pretty interesting ways.
Jessica Drew would have no problem leading a comic movie - she's already lead a comic, after all. Drew had spider-like abilities from birth, and also has training from both Hydra and S.H.I.E.L.D. Her personality is fantastic, and her work with almost every spy organization under (and over) the sun makes her a very versatile character.
Ms. Marvel (Kamala Khan)
If there is one character that the MCU truly NEEDS, it's Kamala Khan. As a Pakistani-American, Kamala deals with the stresses of life as a Muslim in modern America. Despite this, she's not bitter or vindictive - she works through these difficulties with an energy (and a little bit of awkwardness) that few heroes or heroines could match. She's far from any stereotypes, and is quite possibly the geekiest person in the Marvel Universe, rivaled only by the legendary Phil Coulson in her knowledge of superheroes. Plus, as Carol Danvers' successor as Ms. Marvel, Kamala could be introduced very easily through another female lead film - a huge first for the MCU.
A bit of an odd pick, I know... but if Tony goes heavy into drinking (i.e. Demon in a Bottle), someone is gonna have to put on the armor. I've always enjoyed Rescue as a character, and love the armor design. Pepper stepping up to fill Tony's gold/titanium alloy boots would make for an interesting plot, and also give Tony a reason to start working past his alcoholism. If there is another Iron Man story, I wouldn't be surprised to see this iconic storyline on the table - and hopefully, with Pepper taking a lead.