Lol, this guy.  I'd be inclined to agree if it were still ~2004.  My opinion, and preference, is both based on observations, conversions (from Java to C#) and working in an analytics department that was 80% java developers and 10% .Net.

We .Net devs would have to sit through the agony of Java lectures about new Java 8 features... that we've used for 5 years.  Or, we'd be asked to migrate tasks from Java to C#, so that our C# team could manage processes.  Often, line-for-line conversions were faster in execution and rarely did we even care to optimize the converted code since time is money.  

Disclaimer: This was for a BIG corporation and our department ran everything strictly on Windows Server machines.  I will concede (from running some personal tests) that there is a fair chance that Java would be on par with .Net apps, or likely better, in OS X or Linux systems running on top of Mono.

Of course, I ran those tests about 1-2 years ago and a LOT has changed regarding .Net on these platforms in the past year since M$ is moving a lot of code to Github.