There is only one 'best' shot on an elk with an arrow, and that is through the lungs, broadside to slightly quartering away. No exceptions. Yes, the frontal shot is lethal, but like previously said "if you can pull it off." That shot is best left to experienced archery elk hunters. When you've got a bull, even a little raghorn (and they're NOt little) coming straight on to you at less than 25 yards, most guys tend to get just a little bit rattled.

Until you're experienced with at least a few bow kills of elk, you're best off waiting for a broadside shot at reasonable range. I just returned from a great elk hunt where I passed up a broadside bull, a 330" class bull, because he was a tad over 50 yards away. Just because a guy can make that shot, doesn't mean it is ethical to do so, and the most important skill an archer should have, is knowing when not to draw his arrow back. I hope you'll take that for what it is worth.