I'm a KB/M user since long time (I never had a console).
I tried both the controls and for my playstyle KB/M is better:
The mouse allows you to quickly change your POV and it's an optimal choice when using the Crossbow and the bombs.

The controller is better for strategical movement and perhaps swimming.
But when I had to face about 12 enemies, the KB/M served me much better.
The only complain is you have to rebind most of the keys and you need a gaming mouse for this purpose: the default keys for combat are quite confusing and impratical.

Very hard not to rant. So only this: keyboard and mouse.

KB/M, never managed to learn to use a controller even close as good.

Controller but now and then will use mouse/keyboard for better control

Keyboard/Mouse exclusively.
My Hands and those "controllers" (any brand) just don't fit together - while a Mouse works fine, and a Keyboard has >100 keys to use! (If the game doesn't mess up)

Seems a controller is much more effective in expert hands : my son (quite skilled at it) just shamed me when I didn't manage to kill some wraith, he plugged his controler and dispatched it easily :o
But as I'm unable to use one effectively, its Kb+m for me ...

95% KB/M

And the other 5% I play when I sit in the sofa in front of the TV I grab the controller (sucks)