I assume you are talking bow hunting.
Tree stands are more effective. But ground blinds are fun to hunt from - you are sometimes having deer walk 15 ft from you at ground level. If the wind is right and you brush in good enough you can get a shot though. Getting busted is easy to do in a ground blind.

For gun hunting, give me a fortress with walls to block out the freezing WI wind or put me on the ground still hunting. Or hunker down behind a big tree. I don't think I would last much more than 30 min up in a high unprotected tree stand with the wind whipping at 20F or colder.