Gonna say some somethings that yin & jamie may disagree.
1. C++ - will get a job anywhere. It is the fastest. It give you more control over everything.
2. Python - If you are doing Data sci or AI this is the program lang for you, its fast looks nice. Its meant to be easy to read but it has its downfalls. The community is trapped between 2.7 and 3+ so its hard to work out if your a beginner what to use.
3. Rust - Doesn't need a GCC, it is as fast as C++ and can be more secure then most C++ as it prevents you from doing dumb things with memory that can get you into trouble.
4. JS (nodejs) - with the V8 engine it can be as fast as C++ because it will offload the code into C++. Super fast to get started with. Made with scale in mind. Supported by cloud functions. Tones of packages. Is biting at heels of python
*Go is also cool because of Ethereum*
1. JS - it is the web. When you learn this you can code front and backend. Has frameworks like reactjs and vuejs which make up the majority of the web. Also combined with Typescript you can get nice looking code and auto completion - documentation.
2. Dart - Soon to be the language of phone apps. Maybe the web (hummingbird js). Same benefits as TS. Is the language of choice by google. It is developed by google. It is also a good backend language but lacks against JS because it isnt supported by cloud functions yet.
3. WASM. Cool. Lets you compile almost any language to WASM and will be really important in 5 years time.
Shit tier list.
1. JAVA - yes I said it, it is fast. and is universal. Full of bugs and licensing issues. The JVM makes running programs a pain. You need a degree to use it and understand the JVM to any full potential. Might also add it requires a package manager that does't have true async downloading unlike nodejs, python, dart... If you end up making a program and somehow start pulling $$$ and you want to use Oracles JVM you will have to fork out "$5,000 for a license for each server processor plus a $1,100 annual support fee per server processor, as well as $110 one-time license fee per named user and a $22 annual support fee per named user (each processor has a ten-user minimum)."
2. Mono - Have you actually tied mono? If someone makes a program directed at windows then try port it with mono it will end up in the shit tier list
My opinion is wrong and so are you.