For me, it is Switch hands down. PS2, PS3, and PS4 (until the Switch came) are my favorites of each respective gen (or half gen for PS4), but being able to play great games both at home and on the go natively and seemlessly has been a game changer. Plus there are several top notch exclusives to boot.
I still love my PS4, but it has been reduced to a side console I only fire up for one or two games a year. There are only a few games on it that both interest me and are not also on Switch.