The “most coveted” meaning “there is a great demand but a small supply, what are the areas of use that are increasing, and where the supply (training etc.) does not follow? :
- PHP: no, it’s almost only used for the Web, poorly secured, not the fastest, etc.: outdated, and the supply of skills is plethoric in France with the worst rubbing shoulders with the (almost, ahem!) best. When a language is as easy as a thumbtack to fix a painting, don’t ask it to be as strong as a screw… nor the handyman to be as good as a welder when everybody can do it: the filter for hiring is too wide.
- Python: yes, AI, blockchain, big data, and so on, it’s useful for everything, or almost, it’s clean, and especially for the future. And in France, where engineers learn Java and non-engineers PHP, there is a lack of Python skills, so it is coveted.
- C/C++ for embedded: electronics is now made in China, CPUs and other languages are faster and faster and you can still do embedded or almost with other fast technologies (java, on OS like Android – Android auto, box, etc.), so less opportunities, and still taught so no less offers (skills): not “coveted” so.
- Java: taught in any self-respecting school, plethora of already trained, a lot of existing in companies, like C# and .Net, in short, there is a lot of work, and a lot of competitors, but being the standard, any other techno (Kotlin, Dart, JS, …) being in its extension, you’ll be hired for your knowledge of java, to learn the latest techno in fashion. Coveted therefore.
- JS / TypeScript/ Kotlin: becomes universal, but like PHP, there is everything: you are coveted but as much for tinkering as a big Node/React or Angular: better than the language, it is the mastery of an ecosystem and framework (react native) that will make you coveted.
- Rust, Go, Dart, Elixir, Elm, Scala, OCaml, Haskel, Erlang, … the mastery (even average) of such new languages and programming paradigms will make you coveted because better than a language, you know how to learn others, program differently, know which of a screwdriver or a hammer is the most appropriate according to the problem, know how to learn another language, and show more intelligence than a follower of fashion … at least for the teams that dare to do better than the others. They are rare, but so are you… and you will find valuable, intelligent teams, a real joy! The anti-PHP or JS catch-all…
- Ruby: or how to learn how to make the web in three months to enter a market that has to maintain PHP and build JS… a growing supply of skills, and a demand that never really took off in France, and that is dying in the U.S. (but perfect to start with, then switch to PHP or JS, or dare Dart!)