I have given up trying to figure out 'eternity'. Top votes for me are;
1) Reincarnation
Seems to make some sense. Either the Buddhist idea of samsara or the gnostic idea of the Black Iron Prison. Trying to escape the samsara/prison and all that.
2) Annihilation
Could kinda go with reincarnation in a way but I sometimes have doubts our personalities survive death so perhaps it's just our essence. So whether we move on or not, our personalities that are experiencing the here and now possibly won't exist in our next stop. Or it could just be that we cease to exist all together, but I doubt that. My journeys have lead me to doubt that there isn't at least a small piece of us that moves on.
3) Daemons, HGA, Groudhog Day
This one is rapidly gaining ground in my books. The idea that we live the same life over and over. Kinda like the samsara but we don't really change in each rebirth, we just take what we gained in our last life and apply it to the next. Of course we don't remember our past lives, but it's in our unconscious. We can learn alot by tapping into our unconscious and learning from our 'higher self'. There are many names for the 'higher self' from Daemon to the occultic idea of the Holy Guardian Angel. Basically this being, which is really us in a higher form, knows everything about our lives and tries to help us live that 'perfect' life. For what ends? Who knows... The dangers of this path can be that you are pretty much 'hacking' your mind and conscious. Sometimes with detrimental effects to your brain. Although if you're persistent and have some techniques for controlling your thoughts you should be ok. Whether we are meant to delve into our unconscious life this is up for debate. Perhaps it's like skipping ahead our 'place in line'.