Ask HN: How to decide which language to use for my life dream?

I want to finally start the web app that I always dreamed of doing. My hope is that it will become my startup and eventually my life mission. When this is what I'm aiming at, I find it very hard deciding what language to use... I'm pretty determined to start with google app engine (and maybe later move to compute engine) so it leaves me with 4 options really. Here are the pro/cons of using them: 1. Java: my comfort zone. It will take me relatively little time to get going because I have the most experience with this choice. Also, it's a solid choice in terms of performance. 2. PHP: my other comfort zone. It will be the fastest to make a working prototype, so why not really? Since it's app engine, I don't need to worry about scaling it. But then again, I don't like writing PHP... 3. Python: I don't have much experience, and besides I don't really see any advantage for python over php. The plus: if my site fails, it will be good to learn python... 4. Go: it would be really cool... But it's experimental, and I'm not so sure how much time it will take me to take care of basics such as templating and user management...