Which are the players who won most Man of the Series awards in international cricket including Test, ODI & T20.
Sachin Tendulkar holds the record for combined (Test, ODI & T20) most player of the series awards in international cricket with 20.
From stats.espncricinfo "Most player-of-the-series awards":
Disclaimer at the end reads:
Series awards have not always been a regular feature in internationals and the list may not be complete for matches prior to the 1980s
Sachin also holds the record for combined most player of the match awards with 76.