I want to die by drowning. If I was ever terminally ill, I would take care of my family as long as I could, then just walk out to the ocean and let it take me over. Of course, since I love swimming in the ocean, I would probably live through it and die in a hospital bed.
I chose being burned alive. Fuck that.
but, the worst way to die would be in a hospital bed with everyone standing over you and looking at you with those sad eyes. Having no strength to get up and kill yourself, you could just lay their and wait to die, the waiting would be the hardest part.