Should I write in my native language or my second language?

The argument pro native language is that, well, I'm a native speaker and I know the subtleties of it, especially when composing dialogue.

The argument pro second language is that my vocabulary is vastly superior and I will be capable of constructing better, more professional prose (as opposed to the simpler yet more natural style in which I write in my native lang)

I made a thread about this a few days ago but it mostly went unnoticed.
Help, it's literally the only obstacle right now.