In my sleep.
In bed on a lot of painkillers so it doesn't hurt or in my sleep.
Another one of these.. well I wouldnt, as in never die! Immortal! Even if the whole universe around me was gone and I alone was waiting in the void, Id have eternity to try my hand in trying to create another one. Now that would be something!
Pretty sure an Opiate overdose is the best way to go, you feel all warm and fuzzy and slowly nod off then fade away