C# is a language that learned from Java's mistakes. So as far as the language goes, it is a bit cleaner. Java's biggest asset is all the code that has been written for it and the fact that it is cross platform (C# is getting there).

Really though, I think Java's biggest asset is the JVM, there are so many great languages other than Java that run on the JVM; Scala, Clojure and Kotlin being the most notable.