Let's discount all metaphysical theories like religion for a moment. You have a couple of options under a purely physics-based, naturalistic, nonreligious system:
1. Eternal recurrence - Everything repeats identically forever. This might be because the universe is a closed system and Poincaré recurrence applies to it, or because the universe is infinite in duration and span and there is a copy of you trillions or quadrillions of light years away, or because the ultimate structure of reality is that of infinite universes nesting inside black holes or whatever. The hitching point here is whether or not a copy of you would be you, and are whether it would be condemned to make the same choices or whether it might make different choices.
As a kind of subset of (1a), a Boltzmann brain is also a possibility, albeit a horrific one: your brain might spontaneously emerge from the quantum chaos at the heat death of the universe, given sufficient time. These brains would exist for microseconds before being fried by the radioactivity of the dying universe.
2. Quantum immortality based on Many-Worlds Theory of quantum mechanics - you can't actually experience death. The wave form never collapses
3. Generic Subjective Continuity, or Open Individualism - Just ad the concept "redness" doesn't end when the apple falls and rots, so too does conscious experience resume elsewhere, albeit in another form. Nothing would necessarily be transferred - no memory or spirit or essence, no past life regressions - but the simplest possible conscious state at the moment of death might be sufficiently similar to that at the beginning of life for some other organism so that consciousness resumed within it, stripped of all memory and all experience.
4. Infinite nothingness - But this would not be blackness, I think, because to perceive blackness implies a perceiver. Rather, the closest human analogy I can think of is being put out with anaesthesia: you literally do nor experience anything.
With the first two, what you need to ask yourself is whether you believe a copy of yourself would indeed be you. This is the ship of Thesus paradox: does a ship in which each individual plank is gradually replaced remain the same ship? When Kirk and Spock step into the transporter on the Enterprise, do they die each time they are molecularly disassembled and cease to exist? If you believe no, then it follows that under these conditions you should expect to experience yourself as yourself again. If yes, move to number four for all practical matters.
I'm also not sure all of these are mutually exclusive except for the last. Eternal Recurrence is probably compatible with Open Individualism/Generic Subjective Continuity - One continuous span of awareness oscillating forever.
There are complications, from a human standpoint, with all of these: straight eternal recurrence seems like it would be monstrously unjust to those born which in bad circumstances, either genetic or social, or to abortions or to those with bad lives etc. The slave would always be a slave. The aborted fetid would always be an abortion. Etc. Straight quantum immortality would seem to lead to a hellscape of ever-degrading physical and psychological states. Infinite nothingness would suck for those who love their lives, or who want to see a loved one etc. again.
But all the theistic options suck also. Does even Hitler deserve a he'll of infinite duration? I mean a He'll which literally never ends? No, I don't think so. Would Heaven, after a multiplex of years, still be all that exciting? I doubt it.
From a purely human, moral standpoint, what makes the most sense to me from an ethical and desirable element (which may not be how the universe works at all) is Open Individualism. Hitler's eyes point of view will experience that of every Holocaust victim, and every Holocaust victim will experience Hitler's point of view. The rapisr will be the raped, the hunter the hunted, the savior the saved, etc., so that the total value of the system is nil.
Now, that sucks if you're one of those who wants all experience to end forever. However, that would mean that the problem is not with experience, but just with you. If "you" cease to exist in this life tomorrow and "you" open your eyes again as a sentient squid floating around in the upper atmosphere of a gas giant six hundred million light years away twenty billion years from now, and "you" perceive things as just fine from this new perspective, then what did any of it matter in the end?