Personally I like Java a lot. I like Python for rapid prototyping and particularly code where numpy and scikit-learn can do the hard work. PyPi helps w/ branchy semantic web workloads but for things like that (say something like https://github.com/srdc/ontmalizer that really works which I've had on the agenda for the last year) I'd pick Java.

I’ve worked for numerous companies including startups that used Java or JVM languages like Scala.