The ease of acquiring/accessing each method varies a bit depending on circumstance to the point I wouldn't declare one method to universally be the "easiest". As for lethality, I believe the following are around or above 90% if done correctly: sn, n, nitrogen tank, ddmaph, shotgun in mouth, and jumping higher than 12 meters (40 feet) onto a hard solid surface. Of these N is basically a pipe dream these days, ddmaph requires a lot of illicit drugs, and nitrogen tank method is very expensive. SN and jumping are for most people going to be the most accessible, though in the united states guns are arguably easier to get these days. Many would argue SN is easier to perform, since swallowing has less SI to fight than gun and jumping. SN also is "more forgiving" in the sense that the few people who do survive gun or jumping can wind up horribly mangled for life, while surviving SN is relatively not so bad. Finally there is the moral angle -- some people aren't comfortable with jumping since random passerby might be traumatized by the body + there's the risk of landing on someone. There's of course oodles of other methods. Many strangulation methods exist and are highly accessible but have relatively higher failure rates due to people's SI kicking in. This is all theoretical discussion and not advice.