GearWrench ratcheting wrenches. They're compact and fit in places that sockets never will. The ratcheting mechanism is very fine, with low backlash, which matters a lot in those tight places. They feel great, and they're a delight to use.

Wirewrap tools. They're mechanically simple, easy to learn, and let you create neat, dense hobby prototypes faster and easier than soldering.

Wago Lever Nuts. These let you join a wide range of wires, from 24 to 12 AWG, stranded or solid. They're quick: strip, insert and flip. They're verifiable: you can check that it's done right just by looking at it. They're reliable: the spring pressure ensures they never come loose, even with vibration and heat over many years. I'm never going back to twist-on wire nuts.

Ruby. The seamless blend of OO, functional, and imperative programming is beautiful. It can be dense without being obscure. irb and pry make it easy to explore code and data. The syntax is mostly conventional and easy to learn. The standard libraries are well designed, and have consistent interfaces. The documentation is concise and easy to scan. I won't say its "The Best", but of the dynamic, interpreted languages I know, Ruby is the most fun to use, and it starts with the clean, well-considered design right at its core.