I'm surprised at the number of people citing Renai Revolution 21, The Manpower, and Love Machine, as good MM dances. RR21 is a dance only in the sense that the Macarena is a "dance": There's a lot of arm movement, some upper body movement, a bit of simple side-to-side hip-shaking; but VERY LITTLE leg or foot movement. And when they do move their feet, its a simple side step and back. The Manpower is a bit better. There's enough foot movement to call it a dance, but its actually among the simpler MM dances. Love Machine is in a category all itself. It also has very little foot movement, but the other movements they are making are so comical and fit so well with the song, its a visual delight anyway.
The Peace is by far the best MM dance. As you can see in this dance practice video, in which the camera never moves and you can see their entire bodies the whole time, the Peace is much more complicated and has a wider variety of steps and movement. (I notice, though, that the choreography is designed so that the weaker dancers don't attempt the harder, quicker, steps. ) Rika is the "star" of the dance (she's the one in all yellow) and deservedly so. She's great in this dance.
The best H!P dancing I've ever seen is in the Tampopo song "Oujisama to Yuki no Yoru" with the line-up of Mari, Kago, Rika, and Kaori. Kaori is a bit tentative and "small" in her movements but the other three are great. Here's a dance practice video that shows every move of all four of them:
The best dancers ever in MM are Rika, Mari, and Kago, in that order. If I had to pick a number 4, I'd pick Hitomi Yoshizawa, but admittedly she's significantly behind Kago in her abilities. (Admittedly, also, I haven't looked carefully at the dancing of the post-4th-generation musume. )