Pros of jumping: Jumping is faster. It's all over in a few seconds. SN takes about half an hour to take effect, and it can be somewhat unpleasant for a while.
Cons of jumping: (1) If you don't do it from a sufficient height there is a real risk that you will fail and be left very seriously injured. (If you jump from a great height, there is still some risk of surviving, but it is small.) With SN, although there is theoretically a risk of brain damage if you survive, in reality that seems to be a very rare outcome.
(2) Once you have jumped, you can't change your mind. You sometimes can wth SN, either by forcing yourself to vomit, or by calling an ambulance.
(3) Most people would find it harder to jump from a height than to swallow a glass of salty water.