I love the question "what technologies/frameworks should I use to build my new product?" because it is one of the only questions for which there is almost always one correct answer for everyone. That answer is 'whichever lets you get a minimum viable product released the fastest.'

To sorta-quote Eric Ries, most products do not survive their first encounter with the users. You should use whichever tech you are the most agile with and get a concept app out and into people's hands as fast as possible. After you pivot 15 times and actually know what your immediate and near-term requirements are...THEN you can start looking at going off into new territory if there's a better solution than PHP for your particular case. I'd be spending much more time trying to be sure that you are building something that people actually want and that you can create a business around rather than learning a new language. I'm happy to talk over strategy anytime :0)