Hulk deserves another solo film, especially in a post-Avengers MCU.
I also want the following solo films:
Black Widow (with Hawkeye and Nick Fury as supporting characters)
Scarlet Witch (with Vision as her supporting character, maybe House of M film)
Venom (after being established in a Spider-Man film, with Carnage as the villain)
Spider-Man 2099
Spider-Woman
Ghost Rider
Nick Fury: Agent of Shield
Silver Surfer (assuming Marvel gets the rights back)
Black Widow is a strong possibility to replace Inhumans slot in the Phase 3 schedule. It could be set within the context of the Accords post Infinity War, seeing Natasha operating as a mercenary, and featuring an exploration of her dark past, her relationships with Clint and Nick getting strong focus, with Yelena being one of her antagonists.
Venom is very possible, but he won't be a villain in such a story. I could see them doing an Agent Venom thing more than classic Venom, though.
Spider-Man 2099 maybe, but probably around Phase 5 or 6 time. It could be a great, refreshing, left-field movie. It could have a connection to the wider MCU via the future Spiderman seeking to warn the past about the future via time travel or some such.
Silver Surfer is a good chance if they get the rights back. Focus on his ambivalent relationship with Galactus, his life as Norin Rad is pretty essential to establish before we get to him becoming Galactus's herald, and his journeying across the universe.
As for a Scarlet Witch movie...I would like to see it but sadly I think it's as likely as pigs flying on jet-powered pencils with glowing lead.
House of M is way, way too controversial; it's been accused of being misogynistic and stigmatizing mental illness in an extremely nasty way. I don't think Marvel Studios wants to be pilloried by mental health charities; Disney does not want that on their plate. It's too problematic. Also, 616 Wanda has never recovered from it, Marvel Studios don't want to repeat the colossal mess the comics division made.
Also, you need either Chthon or Set as the primary villain for a HoM adaptation to work, and you need to establish them first, otherwise it won't work.
Ideally, a Scarlet Witch movie should have Agatha Harkness, Chthon, Victoria Montessi, and maybe Vision, and have a more horror, gothic tone (think Babadook) than Doctor Strange, with a greater emphasis on the supernatural.