With respect to the button in the nitrogen chamber, I doubt anyone experiences regret for pushing in their last few moments. That seems like more of a literary device. I think "relief" would be the common emotion in practice.

For myself, I'm no longer suicidal, but I don't want to be reincarnated, I don't want to go to heaven (and obviously not hell), and I simply don't want to wake up anywhere at all after I die. An endless, dreamless sleep is what I hope for.

I cannot imagine how awful immortality would be in practice. Death, in due time, is a blessing.