You may not buy ps4 now because ps5 is coming on the end of 2020 but the other i think ps4 is gonna get cheap because of ps5. Switch is worth it if you are a big fan of Pokemon and also if you are fan of legend of zelda or not, you will definitely love this game. For me portable thing is not much of a deal because i am most of the time at home but if you travel around places or do job i think this is great.
Ps4 have some great exclusives like God of War, Horizon, Uncharted , Last Of Us, Death stranding(upcoming game), Ghost of tsushima(upcoming game) etc
Nintendo Switch also have great exclusives like Legend of zelda, Pokemon, Mario , Megaman , animal crossing etc
The thing is nintendo switch does not have some great third parties games like Red Dead Redemption 2
If you gonna ask me which should i buy i will say buy both but if you can't you have to decide your own see what exclusives you like more and do some more research on internet.