I’ve been an electrician for over 20 years and my daily bag has evolved considerably, but there are tools I grab every single day. The non-negotiables: a quality pair of Klein or Knipex lineman’s pliers, Klein D203 needle nose pliers, a good set of screwdrivers (I carry individual 1000V insulated drivers for any live work), a wire stripper (Klein 11055 or the Ideal ratcheting stripper for high volume), and a non-contact voltage tester.
The NCV tester is one that some old-school guys dismiss, but it’s saved me more times than I can count. I treat it as a sanity check, not as a definitive test - always confirm with a meter. The Klein NCVT-5 has an adjustable sensitivity mode that helps with ghost voltage issues.
For low voltage work specifically: a punchdown tool (110-blade for Cat6), a cable stripper for network cable, a simple cable certifier for quick testing, and a tone generator/probe kit for tracing cables in existing buildings. The Ideal 62-164 Tone Pro is what I use and has been reliable for years. Invest in a label maker - a Brother P-touch or a Dymo is cheap and the labels last.