I just realized what bothered me about this poll:
It's mixing two things that are completely unrelated to one another:
- The Leader (uppercase) combat role which is exemplified by the cleric and warlord classes
- The party's leader (lowercase); if any
The first three poll options are about the Leader, the fourth is about the leader.
Playing a Leader doesn't imply being the leader of the group. That's just a misconception I've seen frequently on these boards because they (unfortunately) decided that 'Supporter' sounded too passive/uninteresting as a combat role.
I voted 'Other', btw. because I tend to play whatever character I happen to favour at the moment. I don't particularly care if all the basic roles are covered.
IMC, there's is no single leader. Depending on the circumstances and the npcs involved either the fighter, the rogue, the druid, the wilder or the mystic theurge will be the spokesperson for the group.
The wilder has the highest charisma but she is only assumed to be the leader regarding psionic topics.
When it comes to decision-making they're pretty democratic about it. Typically, the fighter and the rogue are the most active and try to force a decision, but that's more a function of the players' temperament rather than their classes' function - which is as it should be, imho.