I share your high regard for C# and the .NET libraries but not your disdain for Java. Java the programming language is pretty ugly but the JVM is robust and there are other languages which compile down to Java bytecode. In your "scrappy startup" scenario I would pick Scala or Clojure long before Python, mainly because I'm skeptical of the idea of using a dynamically typed programming language for large-scale backend development - for human scalability reasons, not performance ones. Personally I'd also have to pass on Windows even in the AAA bigcorp scenario, because I prefer the tooling and open ecosystem around Linux and epoll isn't that much worse than IOCP.