DotNet Core as a whole (C# + F# + other languages that are being ported to compile down to a DotNet binary).
Because it has all the things Java promised us - frictionless, painless, cross-platform programs - but is implementing it far better than Java ever could.
Honestly, DotNet Core is now at least a half-decade or more ahead of Java in terms of the base platform and C# language functionality/ease-of-use. The only advantage Java has at this point is it’s community ecosystem of third-party features and programs.
- David Frum