(instantaneous answer) Sonic screwdriver!
…what? It’s easily the most adaptive technology in the entire universe, able to scan, run computations, operate in various frequencies, move things, lock things that don’t have locks, remotely control highly advanced devices, and even, in rare, specific cases, be used as a weapon, and the list goes on.
I was very tempted by the nanogene machines that can heal entire war-torn planets, but they can obviously create certain nightmares when they malfunction or don’t have enough data but are still trying to follow their programming.
Pretty much every other technology in the series is either a straight-up weapon or flat-out horrifying in truth.
Literally nothing else is even remotely as useful as a sonic screwdriver.
As demonstrated here: