Lung cancer was a very unpleasant death - dragging on for years really. Like in retrospect, I'm sure a lot of the speech and throat problems we were seeing with my brother long before the formal diagnosis - those were the cancer.
And then the final countdown - just flat-out unpleasant.
He was the extreme case though. Apart from the fact he started smoking in different times when it was easy to smoke almost anywhere anytime. So that's how he smoked for a long time (as did I). But he never let up. I remember in recent decades picking him up for various family things, and I would set foot in whatever tiny, poorly ventilated apartment he was in at the time - and it would be ridiculous. He smoked, yes, but also there was a constant concentrated second hand smoke. Ridiculous.
To be honest, I was slightly surprised he put up any fight at all against the cancer. He tried some chemo and radiation. But his long-term behavior seemed to say he was trying to not get old.
Societally respectable suicide, as Vonnegut described it.
But I'm sure your average casual smoker in today's world has a million times better chance of getting lucky and dodging the bullets than my brother did. My brother positioned himself right in the hail.