Interesting that you rate Java higher in maturity of toolset given that C# has Visual studio + Resharper which many believe to be the best IDE experience out there for OO development.
Resharper is made by Jetbrains. The flagship product made by Jetbrains is IntelliJ, a Java IDE and probably the best IDE money can buy. It is also and the thing which inspired Resharper (Jetbrains itself was called "Intellij" previously).
Now, if on top of the IDE, which is at least on par with VS + Resharper, you add things like build tools, project management tools, testing and code coverage tools, Java is basically the Godfather. xUnit, including NUnit, comes from Junit (Java), Nant was inspired by Ant (Java), Nuget was inspired by Maven (Java), etc.
