Wesley Pryce
Angel Investigations
i said Lorne. Lorne was Angels number 1 spiritual adviser,he would guide Angel onto the right path again and again. For part of season 2 he was Angels only friend,and didn't judge him but tried always to help him onto the "right" course. Lorne stayed loyal even to the end,even when it went against all of Lorne's gentle,sweet nature,when he did one last favor for Angel,killing Lindsey. That broke Lorne's heart,but he did it anway,because Lorne may have lost faith in the mission but he always loved his friend. So i think Cordy and Wesley and Doyle and Fred,and even Gunn, despite his "vampire" issues, were amazing friends to Angel,but i think the gentle green demon with a voice of pure bliss was his best friend and his most loyal friend.