website – which one should I choose?

In my opinion, you should first try to understand if you prefer to be a front-end or back-end developer.
If you want to focus on front-ends, I think that html / css / javascripts (and future js frameworks in the future) are the way to go.
If you prefer back-ends, there is a lot of variety too: from PHP or Node to core (C #).
The easiest way to use the fullstack (if you're starting to like JavaScript) is to start with pure Javascript, then go through some front-end frameworks (like React or View), then finish with the back side with Node .js (a language to govern them) everything).