🏝️ Alex
As mundane as it is, I'm partial to Java myself. It's natively cross-platform, has a *huge* ecosystem of useful tools and libraries, is very structured and doesn't have the irregularities of C++ for example, and it does an excellent job of preserving backwards compatibility. Not a sexy programming language, but an extremely functional one for sure.
🎯 Gallium Oxide
And the JVM itself is a marvel of software engineering. Stuff like Shenandoah and the development of Project Loom make it so incredibly versatile.