If An endless cycle of rebirth (or whatever it's called) is the worst case scenario. I don't want to live one life, why would I want to live multiple??
I dunno about that, reencarnating as a cockroach sounds comfy as hell. No consciousness, no societal structure, no obligations or any shiny monkey business that humans take part of; the only worry would be to avoid being squeezed to death by a shoe.
Jokes aside, both the concept of the afterlife and reincarnation would be the worse outcome possible after birth; without the initial birth, both of these concepts are nullified and useless.
Not that I personally believe in any of that; but if by any chance it would turn out to be true, then we would truly be subjected to an eternal game of horror. It already is that, but there's at least relief in the fact that it doesn't seem to be eternal. Some day, the lights will fade.
Another point to add to the reincarnation stuff is the fact that, in order for such a mechanism to work, there has to be a place suitable for life in the universe; with Earth being the only one that we know of so far, this mechanism basically remains nullified as soon as life isn't sustainable anymore... Unless somehow time reverts itself and when you reincarnate you go back to when there was a inhabitable space in the universe. Such a thing doesn't even deserve consideration.
And the Christian afterlife would be even more unworthy of consideration if it wasn't for the fact that it has been drilled into most of us since we were little kids.
Then, another option remains after death - eternal nothingness. This one is still quite terrifying to me, even though I'm a pessimist and I find this whole ordeal of living kind of unpleasant; but I also find the process of dying unpleasant as well.
After you are dead it may not be so bad, kind of like sleeping with no dreams. But it's still kind of terrifying due to the fact that I'm now alive and thanks to having consciousness I can wonder and think about how eternal nothingness will be... Ever since I was little life caused me dread, yet death does too.
It's a game where everyone likes to gamble everything into this one shot, thinking they'll somehow win; but the result is always the same, for every person that has ever took a breath on this earth.
None of the options are my cup of tea - but eternal nothingness is way more preferable to eternal consciousness.