So many greatests. Depends what. Each one is unique in his or her qualities, talents, strengths. How do you (a mortal) measure greatness in Nevuah (Moshe) against greatness in Emunah, Chesed (Avraham), greatness in chochma (Shlomo) against greatness in tzidkus (Yosef) etc.
Each had his own unique greatness.
As WE DO TOO! Each of us (gevald – me too) possesses a unique talent, quality suited for maximum use and need of our particular circumstance, use and need.