I think the one thing people are overlooking is the Guild personality. Each guild has a distinct way of dealing with issues based on its population. Some guilds call people out in front of the raid because they respond better to that time of public criticism. Others pull people aside and let them know their failure is whats holding the raid back and that is enough to fix it.
I do not think its about what is the best way to lead a guild, its about the best way to lead YOUR guild.
Guilds are fragile things built around its members and it is amazing how fast a few incidents can cause one to completely fall apart. Elitism, loot, attitudes, bantering, skills, progression, failure, personalities, sexism, gold, bank rights, gear, leadership, enchants, schedules, gems and ton of other issues all contribute to a guilds success or failure. A good leader knows whats important in his or her guild an should know when to punish or praise based on the 'personality' of the guild.
I think this discussion is like theorycrafting, in that its impossible to consider the specific situation (one side of the story?) in each circumstance and therefore impossible to judge.
A guild is a culmination of its members with its leaders ensuring that its pointed in the right direction.
That was remarkably well said. Bravo =)