There is no better method than N, in second place comes a fairly large caliber firearm (.38 or .375 to be clear, not a .22) by pointing it in your mouth you blow everything up and die on the spot.
After that there are the more classic methods, actually one is as good as the other and you also have a minimum chance of survival by remaining in a coma or waking up in the coffin after an "apparent death."
So whoever decides to catch the bus, especially by the poisoning method, must make a way that his body will never be found again. It is stupid to commit suicide at home, you have a chance, albeit small, of being saved (or worse, partially saved)