Their ability to dialogue, debate, weighing the pros and cons, the willingness to set aside what they want personally and acknowledge what would be better for a majority of players and support that choice as a result.
This. This is key. It doesn't matter how popular someone is, or even how "right" someone is. They have to be able to discuss, not argue and bicker. They have to be able to discuss fairly intelligently. This is why post history is looked at probably more than post count. I know I didn't post much before I joined the Council.