Need help choosing referees

[elven]

Hi,

I'm an undergraduate student now, applying for Master of Public Health(Epidemiology) of Fall 2012.

Now i've already have one referee for certain. i've been doing research with her in the past two years and i'm sure she will give me a strong reference.

But i've got troubles choosing the other 2 referees from the following 3.

1. Professor of a major course.

He just taught me for half a year, and i did quite well in his class. I discussed course-related questions with him through emails, and once led a group presentation. But unfortunately he is an extremely strict man. I'm not sure i can live up to his expectation of academic potential even with an A in his class... Besides he is extremely busy and always fail to check mails in time. Should i ask him for a recommendation?

2.My class counselor.

She might be the person who knows me best, for she has known me since the very minute i began my undergraduate study. But the question is that she only knows me well from a general aspect(overall grades, review from all teachers, student activities etc.) instead of any specific academic point of view. And she is not a professor. Would her reference be a strong one?

3.Program Manager during internship.

I've worked for her since June this year and keep close contact since then. if i ask her recommendation in Oct. then she will know my working ability well(the work is a health-related one). If i'd like one referee to state my working ability and related-field experience, my class counselor and my manager, which one is better?

Sincerely, your help and advice would be very much appreciated. Thanks for viewing~