The choice of language is never irrelevant. Especially if you are launching a start up. You are about to build the foundation of your future development architecture. For example C++ is a great choice for heavy data processing and number crunching, but horrible when aggregating multiple web services or building HTML. PHP is like the opposite and Java is a poor choice for either (imho). Also you will need more developers later on who fit into your working culture. Good C++ devs are likely slightly older than your average NodeJS-Hacker and they care about family and such non-work-related stuff. Haskell guys would probably stay for some late hours to discuss wether their new typeclass is just satisfying a semigroup or fulfills all monad laws…

My advice: choose a well adapted language from the field of industry you aim for: general web/e-commerce - NodeJS/TypeScript, automotive/industry/embedded - C++, finance - .Net/C#/F#, Science: Python