Whatever one does the job you want it to do.
There are wrong answers (some of the esoteric stuff probably not to use for anything real) but everything is so situational and subjective that there is no answer we can give. This goes double if you plan to earn any money doing something down the line. At the same time if you want to join in on an existing project you might well find yourself having to learn what they do, even if only to port it out to something "better".
I would say pick a popular one. Probably best one not tied to a company -- Apple has that Swift thing and objective C but unless you want to find yourself tied to apple then I would probably not.
You tend to have low level languages and high level languages, also web programming languages as nobody really uses the former two to make websites these days. Higher tend to be easier to write, less prone to errors and slower, larger and more memory intensive. Lower level stuff allows you to be small, fast and handle your business (assuming your compiler and OS allows it -- Windows, and MS' compilers this last decade or so have been stripping out things from C family compilers that the most hardcore peeps were once doing).
http://programming-motherfucker.com/become.html is a good resource.
I did cover some in
https://gbatemp.net/threads/so-you-want-to-learn-to-program.371255/
In the real world that means mostly C++. C#, Python, Java (especially with android as big as it is), php if we are counting websites, JavaScript (again mostly website related), Ruby, maybe Perl and that is about it. C sticks around for legacy things and some of the really high end stuff, and if you can handle it then it is a fantastic skill to have. Databases will also crop up early on, especially on websites but eh. C++ is probably still about low level, and C# has its moments (though it tries to make life easier in an awful lot of ways). As well as databases any one of those will have a million ways to spin off -- you mentioned opengl in older threads and that is a whole field unto itself that most programmers won't know and won't care to know, however you probably won't know how to do high end secure software or any number of other things if you spent all your time on opengl.
Lua certainly has its fans, and emulators often use it to allow some quite impressive enhancements to their capabilities, but I don't think it would pick it for day to day stuff. Maybe learn it afterwards, or first if you have a path into something more "useful".
The other things on the first link above aside from HTML (which is actually a programming language these days, was not for for a long time though) have very specific uses (R and Latex being two examples) or were usually made by academics to teach programming to their students and dodge some of the quirks that come with the programming languages mentioned above, and possibly still used by said academics as "it works" and might well represent decades of work to get it to that stage doing a very hard task.
If you plan to be a big boy hacker you will probably want to learn the assembly of a machine you are interested in (PC is X86, Nintendo handhelds since the GBA have been some flavour of ARM, most other consoles since the PS2 have been one of those or some flavour of powerpc, save for the PS2 which was another called MIPS that the PSP, PS1 and N64 also used variations of), and by the time you learn the assembly for your third machine it is all the same really with minor tweaks so eh. Learning a bit of assembly is generally viewed as good as it will help you understand what is going on with the processor and stop you from making if not mistakes then things that will slow your code down.
If we are doing the videos thing then
For an in depth lecture series on learning to program then we often suggest
https://www.youtube.com/view_play_list?p=6B940F08B9773B9F
For more of a fun thing that makes you think about problems a bit that are related to programming (and are usually far quicker) I quite like Tom Scott's the basics playlist (fizzbuzz really is classic and teaches an important lesson).
https://www.youtube.com/playlist?list=PL96C35uN7xGLLeET0dOWaKHkAlPsrkcha