If you ask me, the electrons flow from negative to positive (theoritical current flow direction). But this electron flow is only a phenomenon occurs due to the effect of current.
To justify my answer, there is something called ‘drift velocity’ which is the maximum velocity with which an electron can drift through a conductor. Suppose there is a 1 km long conductor with one end negative and other positive. If you switch on the power supply, theoritically an electron from the negative end will take some time to reach the positive end. But you can instantly sense the effect of current at the ends of 1km conductor.
The conventional current flow has been considered from positive to negative by Benjamin Franklin and we follow the same till today. It had nothing to do with the direction in which the effect of current makes the electrons to flow. Only after so many years the electron flow direction was experimentally found out.
Correct me if I’m wrong.