Li Shenron
Legend
My favourite would be ability score damage, because it's simple to track in 5e (compared to other editions) and still gives enough variety. Temporary or permanent? While the word "permanent" is very scary for PCs, in practice it would always mean "permanent until cured". Temporary gives more mind relief to the players, but a possible side effect could be to turn it into an annoyance that players just soak it up and just wait until it disappears. I would rather have the occurrence of an affliction be more scary than annoying, and prompt some action from the players. So technically I would go with "temporary" and the caveat that this allows me to set all sorts of durations (and even more complex twists such as progression downward or upward) including a duration so long that it is actually permanent, but the real key for me would be to not disclose to the players what the duration is or even whether it's temporary, permanent but stable, or a death spiral: if they don't know for sure, it will be scary and they will act.
As a side note, I totally expected exhaustion to win the poll. It doesn't really work well IMHO, but it's the most frequently talked-about mechanic, and polls drag answers based on trends rather than real opinions.
As a side note, I totally expected exhaustion to win the poll. It doesn't really work well IMHO, but it's the most frequently talked-about mechanic, and polls drag answers based on trends rather than real opinions.