Hall of Fame
Both are abbreviated shots (overhead is an abbreviated serve, the slice is an abbreviated groundstroke). Many say the overhead is harder to hit than the slice but the incoming ball (lob) is limited in its difficulty. Sure if the lob is high and it's a windy day it will be a difficult overhead. But with the slice the incoming ball is uncapped in how difficult it will come at you. Could be deep, fast and with lots of topspin which makes the slice almost impossible to time especially if it's on a fast surface.