I’ve primarily worked as a Java dev for the past 20 years, but I’ve got significant time doing python and one non-trivial Rails app.
The funny thing is I’m most comfortable and I believe most productive in the Java ecosystem, but only because of the time spent working in other languages. Coming back to Java after python, one gets a better feel for what’s essential and what’s cruft. Similarly, when Rails first came out, it can’t be understated how revolutionary it was with respect to web development. Coming from the J2EE universe it was like the true essence of web development had been hidden from us with servlets, JSPs, wars and ears.
That being said - I’m happy being a Java - well JVM at least - developer. The ecosystem is alway changing and often improving, but I assure you it wouldn’t if not for the evolutionary pressures of things like JS & Node, Ruby & Rails and Python & Django.