Who has the most power at SCDP?

The other night when I was watching the latest episode, I started thinking about who I thought had the most power at SCDP. I also wondered what your thoughts would be on this topic, so please share! Here is my list:

Pete: I think that as of the latest episode, he is the most powerful person at SCDP. When Don wanted to fire him in the first season, Bert told Don no because of social connections. He has Roger figured out and under control. And he knows Don's secret.

Bert: He's next on my list because he knows Don's secret. he can't control Roger, so that puts Pete above him.

Now, the third spot is where I get stuck. Is Megan the next most powerful person because she knows Don's secret and she can control Don sexually? (How many women have been able to do that for this long?) I was thinking that just because she hasn't tapped into it doesn't mean that she isn't powerful. She's in a powerful position to get many things that Peggy could never get professionally, especially if she divorces Don.

Or is Don the most powerful (as of the last episode) because of his creative reputation? People come to SCDP because of Don. Still, he has that secret.

With Mad Men, this all can change from week to week. I was thinking that if Harry ever found out Don's secret, that might put him above Megan. It's scary to think about what he would do if he knew Don's secret!