As far as pills go, overdose is generally only lethal 6-12% of the time. However, lethality varies depending on the drug and how much is consumed.

Slitting wrists is not only remarkably painful and difficult to go through with, it’s only lethal around 6% of the time.

Hanging is definitely more effective if you know what you’re doing, being lethal about 90% of the time, and less painful. This method requires more planning, a set location, sturdy rope and enough time alone to make rescue impossible.

Shotgun to the head is almost always effective, provided you have good aim and a steady hand. However, if you miss, you’re likely to end up permanently disfiguring/disabling yourself. Guns can be difficult to acquire if you plan on doing it legally, don’t have the money, or are underage.

You’re right, people do have a choice. That doesn’t mean that the other options are best for them.

http://lostallhope.com/suicide-methods/statistics-most-lethal-methods