Both have their uses, I do like bean bags when trying to get low or from a car. In a hide either a tripod or bean bag. A bean bag is much easier if the hide is busy, at least everyone doesnt watch you trying to setup a tripod in a crowded hide.
A couple of weeks ago I was using a frying pan with a gimbal head mounted to it on the beach, a friend was using a bean bag in a roasting tray... it may have looked strange but it was easy to slide the camera/lens in front of us as we crawled in the sand. Use whatever gets you the images.