My answer might sound a little philosophical.
If making money is your top priority, then you can go for iOS development, DevOps or backend engineering.
If it is not, I would highly suggest adding more knowledge, learn about data sciences, artificial intelligence, or whatever you find interesting. Since you already have good experience, you can freelance to get your money in the meantime. You'll become a more holistic programmer/developer. Try working in a startup for a little less money, you'll learn exponentially more than you would in a large corporation. Frameworks, platforms, are tools to get things done. You could even venture to a product management role.
My honest opinion would be to zoom out and then decide. And there is nothing wrong with wanting to make more money either.