Hi Cassfan,
Good question. I don't have any least faves
But, here are my favorites:
1. The first album cover with and without the exposed toilet.
2. The Deliver album cover
3. The shot of all of them in the pool, I think it was from the Deliver sessions. It was taken by Guy Webster and is in Michelle Phillips's book.
4. The photo of them that is one of the very first group shots of The Mamas and The Papas, also in Michelle's book.
5. The picture of the group in the studio, with the microphones from the Michael Ochs Archives.
Take care,
Nicole