If you're up high looking down, and there's no cover to break up your outline (in other words skylined) your profile is higher with an angled scope.
Except if you turn it to the side, or even turn it down. I personally would never buy a straight scope. I feel you should adjust the scope to your position, not the position to a fixed scope. I think it is way easier to get beside a scope in prone or sitting than behind a straight scope.
