- Better enums

- The way one can plug into JIT code generation via invokedynamic, methodhandles and varhandle bytecodes

- A JIT compiler written in Java (Graal), now pluggable in the reference JVM

- An actual roadmap to rewrite remaining C++ from OpenJDK in Java (Project Metropolis)

- The research being done in Graal and Sulong about using Java to write compiler infrastructure

- Being portable to devices where the CLR probably will never be ported to

- A a better JIT in what concerns dynamic code re-writting

- Multiple implementations, some of them with AOT support, from disparate vendors

I just enjoy using both eco-systems since they exist.