Regarding the most effective leadership style for project managers, naming various styles such as laissez-faire leadership, interactive leadership, servant leadership, transformative leadership, charismatic leadership, and interactional leadership, it's evident that each may be more suitable based on different situations. The effectiveness of each style may vary depending on the context. Declaring one style as universally superior is challenging, as different projects and situations may necessitate different approaches.
In specific contexts, particular leadership styles may be more appropriate. For instance, a servant leadership style may prove effective when focusing on team development and collaboration, while an interactive approach may be suitable for projects with well-defined tasks and processes. Transformational leadership may excel in situations that require innovation and change.
Ultimately, the effectiveness of a leadership style depends on the nature of the project, team dynamics, and organizational culture. Project managers may need to adapt their leadership style based on these factors to achieve optimal results.

I side with @afshinsadri, that the effectiveness of a leadership style depends on the nature of the project, team dynamics, and organizational culture, and project managers may need to adapt their leadership style based on these factors to achieve optimal results.

To add to the discussion, it's essential for project managers to possess a versatile leadership approach that allows them to flexibly navigate diverse project environments. However, it's crucial for project managers to be adept at situational leadership, recognizing when to be more hands-on or hands-off, depending on the project's unique demands.

Like mentioned above, the effectiveness of the leadership style is really dependent on the type of project and how everything needs to be organized. I personally have experienced multiple types of leaderships styles, being able to work at startups, mid-sized companies, and multi-national companies. There were different leadership styles at each due to the nature of their line of work, hierarchal organization, and the overall size of the company.

I can definitely agree that transformational leadership is associated with innovation and change, which can be found in startups, like the one I worked at, and found in companies undergoing a major shift in milestones or recent leadership vision changes.

Project leadership style is one of the most vital parts of a project's outcome in my opinion, I think it is almost undervalued by most companies because they are focused more so on the project succession. There are other parts of the project such as respect and likability of a leader, similar to any group situation in any industry where this is very important. If the project team believes that their leader is unfair or not well versed in the product, then they will tend to base work off their own opinions since they basically know more about the product design than the person leading the project. I have unfortunately experienced something like this in the industry where the project leader was focused solely on the timeline rather than understanding the difficulty of the project at hand and this caused meetings to feel like schedule and timeline updates only rather than any technical discussion. I firmly believe that once you have lost your project teams motivation and respect, it is very tough for the project phases to transition smoothly. Thus, while styles can differ, it is important for a leader to posses leadership, management, and technical skills because it will lead to a more effective project completion process. 

Laissez-faire leadership entails leaders taking a hands-off approach, giving team members the freedom to make their own decisions and handle their own responsibilities. This approach enables creativity and self-sufficiency, but can also result in confusion and a lack of direction, especially in complex projects that demand strong coordination and guidance. On the other hand, transactional leadership emphasizes clear goals, utilizing rewards and consequences based on performance, and adhering to established processes. This style is well-suited for projects with clearly defined tasks, promoting clarity and accountability. However, it may not be as effective in situations where adaptability and innovation are necessary. Servant leadership is a powerful approach that puts the needs and growth of team members at the forefront. By prioritizing their support and development, servant leaders create an environment of trust and collaboration. This gives high levels of employee engagement, making it especially beneficial for team-oriented projects to achieve success. Transformational leadership focuses on inspiring and motivating team members through a strong vision, intellectual stimulation, and being exemplary role models. This style is particularly effective in driving organizational change, fostering innovation, and promoting high performance in complex projects that require adaptable leadership.