Firstly, The Borg. On the one hand they are a hive mind, not individuals with free will. However they also have the Borg Queen, a directing individual that makes the Borg as a whole nothing more than an extension of her will. They aren't an example of a society of free individuals without a leader.
The Organians? What do we actually know about their leadeship or society?
The Founders seem to operate on consensus. The Great Link allows them to operate as an absolute democracy, but their situation is unique.
I do not believe we have ever seen a society of free individuals that operates without a structured leadership, be it democratic or dictatorial people desire (and perhapse require) leaders.
"Star Trekkin' across the universe, On the Starship Enterprise, Under Captain Kirk.
Star Trekkin' across the universe, Boldly going forward 'cause we can't find reverse."
Star Trekkin' by The Firm.