Which leadership style do you believe is most effective in your organization?

One model doesn't work across the entire enterprise since different business units can have widely divergent needs.  System architecture planning is different from security operations, time-frames and skill-sets impact the options for management styles.

I do agree with the Situational. You can't have a static approach but you should be flexible enough to change when needed also for just a while.

My strongest skill is that I can and I'm willing to adapt to every single person I lead. They all have different leadership needs. We are the ones who need to find the way that works with them and not the other way around.
On the other hand, it is also our responsibility as leaders to improve our skills, so we can indeed serve the organisation as intended.

Situational

Situational