Python is fantastic. Truly cross-platform and introduces you to the necessity of third party libraries that you'll need in other languages like C and C++. Java is...Okay...But it's slow and not truly cross platform. Most people on Sythe will likely tell you Java is better over Python, just because pretty much everything related to Runescape is Java (for now - RS3 is all HTML5/JS), but honestly for practical application I'd choose Python over Java. In the long run it'd be best if you could just learn both.