I only have the Wii U Gamepad, Pro controller and the 3DS + 3DS XL.

I would say in terms of functionality and enjpyment I would say the Wii U Gamepad! Theres soooo much things that it can do. My only problem with it is the buttons can feel a bit loose/easy to press, which the Wii U pro controller fixes that problem.

DS3. Everything else is shit.

I gotta say from what I've experienced this entire gen doesn't exactly have the best offerings. I used both Nintendo controllers and the Dualshock 4. Even with the changes, the Dualshock is still an uncomfortable controller, with less than ideal button-response and placements. The WiiU Pro controller isn't that much better, it feels cheap and has small and flimsy buttons. The Gamepad has the same small flimsy buttons, and adds the weight, low battery-life and cumbersome formfactor. I'm not going to count my 3DS, never used it as a controller for my WiiU (is that really possible though?). And besides, it controls like you's expect a handheld to control.

So what wins then? I don't need to use the Steam Controller to know that one isn't going to do it, so that leaves the XBox's controller. I could fairly reliably guess that one's indeed the best, even if I never used it (and provably never will), if it's anything like the 360 controller. Say what you want about Microsoft, I'm not a fan either, but they know how to make controllers.

I think the DS4 feels the most comfortable, but it isn't built as well as the X1 controller.  But Sony has fixed the trigger problem in the newer PS4 controllers so its my favorite, if the triggers were still built like shit I'd probably pick the X1 since my second DS4 woulda probably broke.  The Wii U does feel comfortable for its size, but overall its way less comfortable than the DS4 or the X1 controller and if I factor in the stupid screen on the controller its a very distant third.

PS4 controller

Thats from last gen...

DS4 is my favorite but the build quality is still a bit low. I will invest in a scuf soon cause I Titan-skate a lot.
I would love if Sony made a pro / premium DS4 with really high-grade materials like the Elite.

https://www.youtube.com/watch?v=or_F2Zj_WLA

Titan gameplay from IB.

The Wii U gamepad actually, would like to try a pro controller too

Xbox One Elite is my main. Wish it worked on my PS4 too

Been using the DS4 controller a lot recently, and I love it!

Probably my fav controller of all time, that or Gamecube.