who did the shiites and sunnis believe should be leader
https://www.livescience.com/33071-whats-the-difference-between-shiite-and-sunni-muslims.html
The Shia and Sunni branches of Islam have different beliefs regarding the rightful leader after the death of Prophet Muhammad.
The Shia Muslims believe in the concept of Imamate, which holds that leadership should be passed down exclusively through the Prophet's bloodline, specifically through his cousin and son-in-law, Ali Ibn Abi Talib, and his descendants. They believe that the 12th and final Imam, Muhammad al-Mahdi, went into hiding in the 9th century and will return as the messiah in the future.
On the other hand, Sunni Muslims believe in the concept of caliphate, which asserts that the leader should be chosen based on consensus among the Muslim community. They argue that the first four caliphs (Abu Bakr, Umar, Uthman, and Ali) were legitimate successors to the Prophet, followed by a series of elected caliphs who led the Muslim community.
So, in summary, the Shiites believe that Ali and his descendants should have been the leader, while the Sunnis believe in the succession of caliphs chosen through consensus.