David credits Roger for being the supreme motivator of the band in an interview when he's explaining that it was his motivation and lyrics, not his music, that was missed when Pink Floyd went on with him. He motivated everyone else, gave them the drive to make music, so I consider Roger leader.

Roger also probably credits Roger for being the supreme motivator.

__________________
Tuesday afternoon
I'm just beginning to see, now I'm on my way
It doesn't matter to me, chasing the clouds away
Something calls to me
The trees are drawing me near, I've got to find out why
Those gentle voices I hear, explain it all with a sigh