I am always a little hesitant to make a suggestion for badges but I thought this one might be interesting and there are so few badges based on accepted answers. I couldn't find any similar suggestions:
Awarded for having 100 accepted answer from 100 unique users with a rep of at least 50.
- bronze: 100 answers / 100 users
- silver: 200 answers / 200 users
- gold: 500 answers / 500 users
Name and values probably should be adjusted...