I think it'd be a nice way to go. To just go to sleep and pass into Oblivion. My mom told me a very brief story about how one of her friends had told a mutual friend of theirs that she had heart born the night she died. Her heart gave out as she slept.
Honestly this is the way I would like to go. I'm afraid that I'm going to suffer prior to passing away. I know eventually your brain releases endorphins to help with the pain and eventually you get to a point where you're not even aware you're dying anymore.
When it's time to leave this world, that seems like the best way to die. I don't think I've ever had that fear. As a kid, I more so feared what could sneak on me while I was asleep.