Selenium Webdriver with Java vs. Python
"If you're running selenium tests against a Java application, then it makes sense to drive your tests with Java." This is untrue. It makes no difference what the web application is written in.
Personally I prefer python because it's equally as powerful as other languages, such as Java, and far less verbose making code maintenance less of a headache. However, if you choose a language, don't write it like you were programming in another language. For example if you're writing in Python, don't write like you were using Java.
Generally speaking, the Java selenium web driver is better documented. When I'm searching for help with a particular issue, I'm much more likely to find a Java discussion of my problem than a Python discussion.
Another thing to consider is, what language does the rest of your code base use? If you're running selenium tests against a Java application, then it makes sense to drive your tests with Java.