They all seem to be converging to the same solutions -- either a wireless gamepad, or two wireless motion controller/gamepad hybrids --
GearVR: Bluetooth gamepads / Samsung Rink,
PSVR: Dualshock 4 gamepad / Playstation Move,
Oculus Rift: Xbone Gamepad / Oculus Touch,
HTC Vive: do their controllers have a name? (almost the same as Oculus though)
For the super low cost ones (Google cardboard, or the dozens of Chinese-brand Cardboard/GearVR knock-offs), it would be best to make "look only" experiences... or rely on a generic bluetooth gamepad, though that will severely limit your user base.