Those Caliphs who truly followed in the Prophet's foot steps are called 'The Rightly-Guided Caliphs' (Al-Khulafa-ur Rashidun in Arabic). They are the first four Caliphs: Abu Bakr, 'Umar, Uthman and Ali. All four were among the earliest and closest Companions of the Prophet (peace be on him). They lived simple and righteous lives and strove hard for the religion of God. Their justice was impartial, their treatment of others was kind and merciful, and they were one with the people - the first among equals. After these four, the later Caliphs assumed the manners of kings and emperors and the true spirit of equality of ruler and ruled diminished to a considerable extent in the political life of Muslims.
Source: The Rightly-Guided Caliphs