1. Adam Smith
2. David Ricardo
Tied for 3rd (alphabetically):
Kenneth Arrow
Gary Becker
J.M. Keynes
Frank Ramsey
Frank who? Look him up. As for Friedman and Hayek... oh please... Hayek wrote a very nifty essay that every economist should read; Friedman's inflation expectations stuff is important... the rest is ideology. If you must have a free-market economist on your list, Becker kicks both their asses.
Malthus?! That proto-Trumpian pastor? Smith had already laid out the population theory and way better, and presumably somebody else preceded Smith.