Maven is the de facto standard for open source Java projects, and it still has a reserved seat at that table, but it falls short of what other build systems provide. For example, multi-module projects and incremental builds are more like bolted-on hacks in Maven 3 (I say this with great respect for the work put in by the maintainers). With rules_jvm_external, and other general usability improvements in recent years, Bazel is now quite easy to use. In a corporate context, I think Bazel is a better choice where Java is concerned. I do hope that Maven 4 will close the gap.
