Should I choose PHP or JAVA? For Enterprise Web Application

I think it will be better for you to ask your developer for his advice. If he is an expert in both languages, he should be able to give you advice on which language is better for what you need. If you just want to create something like Coinmarketcap, then PHP will probably be easier but if you want a crypto exchange, you need to think about security as well and it is important that you discuss this with your developer. Also, ask him which language he is most comfortable with for your project.