Another thread on these forums talks about Daredevil's rights returning to Disney. Netflix's treatment was the best adaptation DD ever got, in spite of at least two other tries.
It got me thinking about other characters who've been tried, but have never gotten their due.
The Lone Ranger: Westerns are tricky these days, but it could be done. All previous attempts have been embarrassingly hokey.
Green Hornet: one of the great superhero influences. The Crimson Avenger and Sandman were each almost direct lifts from him. His relationship with Kato would require some work, but it could make for a fun retro-noir piece. The less said about the Seth Rogan film, the better.
The Shadow: Green Hornet's progenitor, and contributor to at least 1/3 of Batman's DNA. The Baldwin movie was visually lush, but intellectually shallow, relying too much on Welles' radio incarnation and not enough on the pulp original.
The Phantom: like The Shadow, the Zane film was visually lush, but more than shallow, was downright insulting. This character supplies another 1/3 of Batman's heritage, plus his mythic, generational elements have influenced The Black Panther. Honestly, with so much history, this one might work better as a streaming series than as a cinema offering.
Others?