"Gamma is a girl's best friend"
- Jennifer Walters aka She-Hulk
Talk about brains and brawn in the right package. Not many people have been a part of the Avengers, Fantastic Four, SHIELD, Fantastic Force, Heroes for Hire, AND Lady Liberators. Oh, on top of that, a lawyer with a degree from UCLA.
Given her powers from a blood transfusion from her cousin, Bruce Banner, aka the Hulk, Jennifer came to appreciate the confidence and assertiveness that had come with being She-Hulk. For a long time, she felt more comfortable in her form as She-Hulk than in her "normal" form as Jennifer. She eventually became comfortable in both forms, and realized that she has much to offer the world in both her forms and went off to become a hero in her own name.
I know I have Thor on the team, but you need more than one muscle-bound hero and She-Hulk fits that bill. She doesn't have the cosmic powers or the magic that Genis-Vell and Thor possess, but what she lacks in those fields, she more than makes up in wit, intelligence, and charisma.