Final answer:
The question involves a philosophical or ethical dilemma regarding the afterlife and choices of existence after death, touching on areas such as religion, social studies, and physics.
Step-by-step explanation:
The question you're asking seems to be more philosophical or ethical rather than based on a specific academic subject. Nevertheless, it appears to touch on notions of the afterlife, which is a topic sometimes discussed within the context of religion, philosophy, or social studies.
In country A, the belief in the soul's eternal journey suggests an afterlife concept, which could offer some comfort to those who are grieving. However, in country B, with no concept of an afterlife, the emphasis might be on the finality of this life and making the most of our time here.
Regarding the black hole scenario, from a physics point of view, being exposed to the tidal forces present at the event horizon of a black hole the size of Jupiter versus a black hole the size of a galaxy, one would face spaghettification either way. But the process would likely be more gradual as you approach a larger black hole due to less intense tidal forces over distance, offering a unique, albeit fatal, perspective on gravitational extremes.
Focusing on the initial question of reincarnation as a fly or ceasing to exist, this is a deeply personal preference that typically aligns with one's beliefs, values, and perspectives on life and death.