David was a great leader because unlike Saul, David accepted anyone. (In my humble opinion, much like Summerville Family Worship Center. It is such a loving and accepting place of worship.) While bringing up leaders, David would get the best out of every situation, and always affirmed his men. He would motivate them with words of encouragement.
David was also very bold and courageous. Even when Adonijah presumed to be king David listened to the Lord. David followed his direction and anointed Soloman as King. David wanted to ensure Soloman succeeded as king and advised him to walk in obedience to the Lord and follow his commands and decrees. David wanted to reiterate this to Soloman so that he know how to prosper and be a great leader. Even a greater leader than David. This is how we all should bring up others, including our children. David had a style of leadership that all wanted to imitate. David was a great example of leadership.