The best tested controller is the XBOne controller. You can also use your VR controllers with vorpX, either as emulated kb/mouse or gamepad.
BTW: You seem so excited to play Witcher 3 in VR that I feel obligated to make you aware that being a third person game W3 defaults to ‘Immersive Screen Mode’ in vorpX, which means you have a (very) huge ‘screen’ in front of you that fills your entire view. That’s about 80% of being ‘in the game’, but not 100%.
Playing the game in what vorpX calls ‘Full VR’ (the 100% mode) requires a first person and a FOV (field of view) mod for the game, so configuring the game for ‘Full VR’ involves a bit of extra work. Instructions here.
You can move it so close that it practically fills your entire view. Personally I would prefer to play W3 that way, but there also in no harm in trying the first person mod. Just wanted to mention that ‘Full VR’ for W3 involves a bit of extra work.
Touch: vorpX reserves one key as shift key on the touch controllers, so you basically have two mappings. The button mappings are shown ingame on the rendered controllers, so that’s quite intuitive to use.