what obscure characters do you think should get turned interesting and into a good character

There are literally thousands of underused characters that a good writer could do a lot with. Here are a few that come to my mind:

Leonard Tippit - I think he appeared in one issue of the Avengers (maybe Avengers 101). Supposedly he is empowered by the destiny force and will one day destroy the universe. Such a threat that the Watcher himself tried to kill him. He went into another dimension as a heroic act to save the world from his future self. There is enough background there to create a good follow-up story.

Hazmat - I loved Avengers Academy and think that Hazmat would be a great character to write about considering the emotional turmoil she went through in Avengers Arena and Avengers Underground.

Black Ant - Life Model Decoy of the deceased Eric O'Grady, the Irredeemable Ant-Man. Natural villain for Ant-Man, Wasp, Hank Pym or the Secret Avengers.

Silverclaw - former Avenger with a supernatural past

Striker - Another Avengers Academy alum with a cocky self promoting personality.

Chase Stein - Former Runaway with low self-esteem who disappeared after Avengers Underground.

Firebird - former Avenger with Human torch like powers who may be immortal.

Spidercide

Blood Spider

Fusion( The one who can create illusions)

Crazy quilt

Clock king

just to name a few.