Whilst I agree in principle about Node being the language of the era. I still strongly suggest that a modern full stack developer should still learn PHP.
As you’ve rightly pointed out in your post, there are pros and cons to both and as such I would be reluctant to have an attitude which requires the developer to choose.
I would go as far to say that, rather than “trying to stay ahead of the curve” or “pick the language that’s going to get you the best job prospects/salary”. Instead of being biassed towards a certain language the modern web 2+ full stack developer should actually be technology/language agnostic and propose tools based on their suitability for the job as opposed to their opinion, taste, usage & popularity data & statistics.