Which was the most common form of resistance among enslaved people?

One form of resistance was slowing down the picking of cotton.  Slaves would intentionally go slower so that they could have an easier time in the fields.  This was combatted by the Southern Plantation owners after a while by whipping the slaves severely during their first picks and then mandating that they had to pick at least as much cotton every time after.

Another form of resistance was to run away.  The Underground Railroad helped thousands of slaves escape to the north and to freedom.