Zebralight Flood headlamp in Neutral White.
Headlamp over flashlight since the light easily removes from the strap and doubles as a right-angle flashlight. Small, light and durable. They even include a spare O-ring when you buy one.
Neutral White Color temp yields more accurate color which is very helpful when terminating cat cables. Adjustable output including three preset levels, and three custom levels. Runs on 18650 rechargeable and lasts a long time on mid power. Flood beam makes rack and underfloor work easier as there is no 'hotspot', just everything in front of you is lit up so you don't have to keep turning your head to move the light to where you want to look. High power is like suddenly being out from behind the rack an being in daylight.
Bonus that the inside of the lens glows in the dark so if you turn it off, it will continue to glow for a few hours.