As ever these things come down to game libraries (including how easy it is to build one, pirated or otherwise, if you are considering that) and future potential there too. The portable or not thing might also be a factor in this -- I have stuck a PS4 in a bag before to go to a friend's and it was just fine. As mentioned the PS4 is approaching something of an end of life as well. This could mean both a flood of them in a few months, and fewer games in the future. That said seeing how abysmal console launches are now then there is the idea of sitting pretty for a few years enjoying what there is while the new console gets up to speed.
For all I rag on the current generation's games I would probably pick the PS4 library for myself over the Switch's current one and most likely its future one as well (E3 is a bit of a formality at this point but will usually serve as a reasonable thing to look at to see what it coming). That is me though and I don't know your preferences here. I should also ask if you are likely to find some funds available so you can have both -- if you are trying to fund this off a paper round it is different to single professional that might spend more on a weekend's entertainment.