I've been programming in PHP for a long time now. I can't remember when I first dabbled with the language but it has to be 20+ years ago.
I'll present my subjective opinions about how the languages compare.
I'm of the opinion that PHP is a tidier, more mature language. I come from a C/C++ background professionally and if you do too, I think you'd find you'd adapt to PHP a bit quicker. Later (PHP 5+) versions of the language are particularly good in that respect.
If asynchronous code is your preference then Node is what you need. Perhaps one of the biggest differences between the languages is the way they naturally lean in this respect.
So, which language should you choose? Well, I'm not going to tell you beyond the hints I've given here. If the choice is entirely down to you, try both and see which one you prefer and which one best meets the requirements of the application you're developing.
Try not to fall into the languages argument. There are a multitude of opinions about one language being 'better' than the other or one language 'dying out' and other such comparisons. Most of it is tosh. If you have absolute choice — by which I mean the choice of language is not dictated by corporate policy or a specific need — it doesn't matter. What matters is the application you end up with. Users generally don't care what language something is written in. I'll stick my neck out and say both Node and PHP will be around for the long term and you have no fears in that respect.
I'm quite language agnostic and, for my own projects, I often pick the language based on interest alone. I've probably programmed in a dozen languages in my career and they're all, with the possible exception of assembler, pretty much the same. They all consist of variables, loops, control structures, functions etc. and all you need to do with a new language is become orientated to the environment. I've never understood why job applications sometimes require specific language experience because, really, it's only the work of a few weeks to become orientated. Just pick the developer with the best understanding of programming paradigms and design specifications and you won't go wrong in the long term.