Indeed, JVM and .NET are the only two major ecosystems out the whole Xerox PARC ideas[0], and the reason that to this day they are my two main workhorses, plus JS runtimes, because Web.
[0] - Technincally Objective-C and Swift could also be considered, but they lack the industry wide adoption, as many cool tools only exist in Apple land.
Swift is quite good. I assume the tooling is catching up to Objective-C. It has been a couple of years since I had to solve something with Swift.
Any reason, apart from outside requirements, to pick the .NET CLR over the JVM as a runtime in your experience? Outside of library/framework support, which I've heard is good with the CLR.
[0] - Technincally Objective-C and Swift could also be considered, but they lack the industry wide adoption, as many cool tools only exist in Apple land.