Also, everyone reading this should ask themselves what they would do if they were a doctor and this happened to them. I freely admit I would choose the person I was closest to. This is an entirely normal reaction. No one should be ashamed to admit it.
I agree, all things being equal, there would be nothing wrong with choosing a friend over a stranger. The harder question might be: Would you choose your friend over a stranger if, say, all things were NOT equal? For example, what if your friend were 60 years old and the stranger were 25? In that case, I might have to choose the stranger.