Most people use thermal for hunting ... it is best for seeing critters that are alive.
Night vision (a.k.a. image intensifier) is more flexible, used for stealthy navigation, via foot or vehicle and for shooting.
Both sorts come in three general flavors, rifle scope, monocular and clipon.
Thermal cannot see through glass, so cannot be used to drive vehicles with glass or to see through windows.
NV cannot see well into shadows without moon light or separate ir-illuminators to help.
Thermal is not affected by visible light so can see regardless of (visible light) shadows.
==
Ideally a combination both is good, because the two technologies complement each other.
So, it might not be a question of "which" ... but maybe "which one first".
==
What sort of critters will you be hunting?