Ideally between 7 and 18 yards... thats how close I want them. How close/far I can and will kill one is a different matter. I want to kill them in tight.... I want to see the whiskers on his nose and the cedar peelings on his bases. This is the whole reason I bowhunt.... getting in tight.
That said... I'm not going to let a big deer come within 40 of me and not shoot if I am comfortable with the shot and he presents a good opportunity. There are days I am confident at 50yards and days I don't feel like I could hit the ground from 30 yards... just depends on how I feel.