It doesn't really matter. After knowing a few, you pick one up in a few months, and the rest will come with use. Looking out for trends won't help, as you can get only limited experience without using a language for solving real problems.

Solving Project Euler or HackerRank in a different language is fun, but does not really teach you a language. Languages are more than languages, they have ecosystems and conventions around them, and many of those come up only when doing larger scale problems to solve real problems. Few people do it for themselves as a hobby, most do fun stull as hobby, and do these as work.