Love stump. It's the only WM I found that gives first-class support to full screen. You are never "locked-in" when you go full screen as you are with i3. Even dwm locks you in with fullscreen video games.
If you know lisp then you can use stump to emulate i3 or dwm down to every last detail in about 25 minutes.
Pretty light running on Clozure-CL. 30 MB. I rotate between stump and dwm quite a bit.
It's been done to death, but Common lisp. If you're looking for a new magic shiny you will find it here.
You develop in a parsed environment, not raw text. Tooling will allow you to make structural edits instead of traditional text edits.
Everything is an expression and can be used as a value. Even loops and if-statements are expressions that can be assigned to a variable.
Macros. You can create languages. Change rules and syntax. Do performance optimizations moving processing to compile time instead of run time. To process matrices you create an intuitive language to handle them, rather than shoe-horning into a general purpose language missing low hanging optimization-fruit.
You develop against a running program. Other langs can do this but they are missing the first rate tooling or the community doesn't do things that way. While you develop the 4 times become 1. Thinking time, Typing time, Compile time, Run time. Try an idea, get immediate feedback. Your design medium is play-doh so design by making something tangible you can feel. In other langs your medium is marble so you plan it out ahead of time before you mess up your expensive marble block, then waste hours/days before you realize all your unit tests were made against a flawed API.
So much time and energy is wasted protecting marble. Play-doh is better.
For the DB use postgres to save licensing costs. I would be more adamant about the DB decision than the language. It's nice to be able to deploy unlimited postgres DBs on as many servers as you need without breaking the bank.
In the future you may have ancillary services/apps better off using a separate DB for performance. DB licensing costs will influence your design decisions so remove those costs from the equation.
C# is fine though (even on linux) and will give you reasonable performance, likely better than node.js is most cases.
Every software that's widely used and isn't a crap gimmick is written in C/C++.
Android/Linux is mostly C. Google Search-C++. Web browsers-C++. Java VM is a c++ program. Games-C++.
The only place Java/Ruby/Python/etc has a foot hold is in websites providing crap gimmics that are just wrappers over C/C++ programs. Like uploading a photo or tweet, just providing some glue over all the C/C++ programs that actually do the work.
There's a reason people are voting with their feet in the millions for our capitalist country, not their socialist.