On their native consoles, XB1 controller easily since I like the ergonomics much more, the battery life is (a little) better and the extra features on the DS4 are rarely used effectively. Also don't like the Playstation stick format. Switch Pro I like the great battery life, the rubberized grips are nice, but it doesn't fit my hands as well and the D-Pad is bad. I also don't like how much less reliably it turns on the Switch itself, always have to mess around with it for 15 seconds.
On Steam, I found more use for the DS4's motion/touchpad with all the customization available. Control media, voice chat, map save slots, etc. without having to rely on multiple button combinations as much. And occasionally actually use the gyro for a game. I probably have still used the XB1 controller more though.
So yeah I like aspects from them all, definitely would like some hybrid form more than any individual but I'd generally just give the nod to the one that feels best XB1.