Well, it really depends on a lot of things. I like to actually aim a little low on the chest, say about 2/3 of the way down from the back. You should bend at the waist when you shoot from a stand. This keeps your anchor point and form true instead of droping your bow arm to the deer, which causes your anchor to change and will make you shoot high. I just like aiming a little lower. When you got a big buck in front of you, the last thing going through your mind is whether you have good form, you tend to get pretty rattled. But, if you draw level, and bend at the waist till you are on target, you will hit dead on.

Practice as much as you can from a stand. You will see where you are hitting when bending at the waist. Also, just drop you bow arm and shoot, you will see what I mean, you'll hit high.