Team 423's most used tool would probably be our 7/16" ratcheting wrenches. We have at least 3 of them and a few non-ratcheting wrenches, and there are still never any in the drawer.
Our favorite tool is probably our spring-loaded wire strippers (like the picture but with yellow handles).
They work really well and choosing what size wire you have is easy even without the gauge labeled on the wire. Probably not as easy to use as the gauge-agnostic strippers posted earlier in the thread. We call them cachuk-cachucks after the sound they make when you use them. That sound can be heard from any spot in the room throughout our meetings, even if no one is stripping wires, simply because it's fun to use.