Which is the most liquid measure of money supply?

M2. M2 consists of M1(coins, bills, travlers checks/checkable deposits), savings accts, money market accounts, demand deposits, and timed deposits. M2 is less narrow than M1, therefore being more liquid/spendable.

*The Fed has defined three monetary aggregates M1, M2, and M3. The narrowest definition, M1, includes the transaction deposits of banks and cash in circulation. M2 adds savings accounts, small time deposits at banks, and retail money market funds. M3 adds large time deposits, repurchase agreements, Eurodollars, and institutional money market funds. In March 2006 the Fed discontinued tracking M3 because it does not convey information about economic activity that is not already embodied in M2