The reason we hunt from a treestand is obviously scent related. Personally, I feel the higher the better. This is determined by terraine etc but if you can get 20+ feet of the ground, it should be better then 15 feet. I go as high as I can but never above 30 feet. I feel that, under normal conditions, the higher I am the better chance the deer will not detect my scent. Also, if any hunter is "afraid of heights", 12 feet off the ground is better than ground level.