[ahmedfromtunis]

It doesn't matter. All that you need to focus on is building a product that users want.

For (almost) every language that exists, there's at least one startup using it that succeeded.

The argument of speed is not realistic. Time matters, that's true, but not to *that* extent.

Maybe the only factor that matters is how familiar you are with language (so that you can easily build your prototype/MVP) and how popular the language is so that you can easily recruit when the time comes.