Hello Giacomo,
In Spain the most wanted developers are .NET and JAVA developers. It's true that they are starting to lookg for Node (JS in general), Python and other technologies developers. But .NET and JAVA fill most vacancies. You won't have any problem!
About the salaries, like always it depends on your skills!!! If you are a junior (regarding my knowledge .NET friends) about 25K gross/year... since this, you can get 30-40-50K gross/year...
Take a look at linkedin and http://infojobs.net
And if you like i know some recruiters specialized in .NET jobs Just tell me and can tell you the names or websites.
Best!
Carlos
PS: I'm not a .NET or JAVA developer. I'm a JS developer and loving it 