Writer's Preference?

Most people cannot believe that he severed ties with the most important individual in his life, his daughter. Comma, colon, or dash after 'life'? Or are all acceptable?

1, 2, or 3 -- or can each be punctuated with the dash, comma, or colon?
1. There's only one man who can do that job, Mike Smith.
2. There's only one man who can do that job: Mike Smith.
3. There's only one man who can do that job -- Mike Smith.

Same question -- 1, 2, or 3 below, or can each be punctuated with the dash, comma, or colon?

• I am writing this letter on behalf of an individual for whom I have tremendous respect, Danny Thompson.
• I am writing this letter on behalf of an individual for whom I have tremendous respect: Danny Thompson.
• I am writing this letter on behalf of an individual for whom I have tremendous respect -- Danny Thompson.

Thanks.