In fact, the issue of leadership in the Muslim state is meant to secure people’s benefit and interest. In the early days of Islam, Muslims used to fix the issue of Caliphate in a good way. Always, sincere Muslims give due attention to Muslims’ benefit over their personal benefits.
Differences could naturally happen when choosing the ruler; but these differences in opinion should be expressed through peaceful, fair channels.
Throughout history, you will see good examples and bad ones. It is important to differentiate between people’s stances and Islam. Also, it is important to understand differences and opinions in their contexts so that you could fairly judge others.
However, for details regarding such an important topic, one is advised to read a reliable Islamic book that deal with As-Siyasah Ash-Shar`iyyah (Shari`ah-Oriented Policy). We recommend here, for example, Dr. Qaradawi’s State in Islam.