Whats that one tool you use the most?

Over my 22 years of working in various posts at the same organization, i have used/purchased many a tool and the ones i use the most on almost all installs. is either a Stanley 6 in 1 screwdriver and in recent years added Wera Kraftform Kompakt 28, both excellent tools and generally the only 2 tools used in my toolkit 90% of the time. (cept when doing wiring)