Definitely David. David was the only man that God called "a man after my own heart" and was able to pull in New Covenant blessing into his relationship with God. God allowed David to enter into the Holy place in the temple, even though he was not a priest, and it was illegal according to God's law established in Israel. Any person that entered this Holy of Holies in the temple if they were unclean or not a priest would immediately die. But because of David's burning heart for God, God seems to have made an exception. David was able to tap into God's heart, His intentions to redeem His people from sin and bring them into His presence. He brought a new covenant blessing into his time.
David also had amazing character shown when he had multiple opportunities to kill Saul while being chased for more than 10 years while Saul tried to kill him. It was prophesied to David that God would deliver David from Saul, yet David was able to recognize Saul as someone God anointed and made king, and was unwilling to go against God's established authority. He was patient enough to wait for God to do it, and recognized the opportunities to kill Saul, as not being what God wanted him to do.
David sinned, but David was able to repent and be restored as the generational seed of Jesus, where God calls his own Son the son of David. David's life stirs my soul into hunger for God, realizing that David was able to have his relationship with God with an inferior covenant than the one we are live in.