I'm quite surprised that I'm the only one (at the time of writing) from the poll whose biggest fear is actually being dead.
For me, the rest is temporary. Potentially awful and abusive, but finite. I am frightened of the (potential?!) permanency. I'm scared of subjective continuity. I'm afraid that there is a god, and that they're cruel, sadistic and unforgiving. I am worried about technology and human interference of my consciousness.
No matter how well-read you are, the size of your platform or how many big words you use, no one knows what being dead constitutes. I have my hopes set on returning to the void I came from - complete unawareness, repaying some of the energy I took up whilst being here through my decaying corpse - but the uncertainty of what death is, is a big fear of mine.