General question on choosing an Assembly language based on my goal So I know assembly is so big and it seems learning assembly is like learning high level programming, you don't need to learn them all, you can learn couple and this will be enough.

The thing is with high-level language it is easier to grasp and implement in your life. But I am having hard time with assembly, I learned ARM at university, but I am not sure which version it was. And, it wasn't practical in real life. Also, it was too primitive. It doesn't even help me read other assemblies. Because when i read other assembly, I am lost seeing too many new commands that I have never seen before.

But I want to learn a language where I can add it to my code or make stand-alone version out of it easily like C++ or C# for Windows, so basically a practical language, also a language with live community and not an abandoned one.
i learned some programming languages and they are useless for me like CLIPS, ADA and Prolog.

So what are the useful and practical assembly languages out there to learn for windows. Is FAsm a good start? Also note that I do not know what I want to do with it, I will learn it them when I get good command of it I will decide, I may use it for images, or AI project or anyother use where my path will lead. I already know C++ (i use it for UE4 and AI code implementations), C# (desktop/web) app and java (desktop).
There is very, very little need for assembler. For is very rarely need for inline assembly - for example, I have some code somewhere that calculates (a * b) / c for unsigned 64 bit integers where a * b overflows. 

And asking "which assembler should I learn" - if you ever need assembler, then that's the one you need to learn. Any other assembler is useless. 

The only case where you really need to use assembler is at the extreme ends: When you are creating a virtual machine, you need to understand the extremely rarely used instructions to do this safely. If you create codecs, or encryption software, where you have very small amounts of code using up huge amounts of CPU time, that's where you may need assembler. But you don't need to know just assembler. You need to know and understand CPU instructions that have been created exactly for these purposes. You are in a highly specialised area there.