With the recent proliferation of Java Virtual Machine (JVM) implementations, it's difficult to know which implementation is the best for your use case. While proprietary vendors generally prefer Oracle Java, there are several open source options with different approaches and capabilities. Given how the implementations vary in some underlying technical specifics, the "correct" JVM implementation will vary based on the use case. Apache Sling, in particular has some specific needs given the complexity of the OSGi / JCR backend and the Sling Resource Resolution framework.