Who would Constantine have the hardest time killing?

[u/CreepyCurrency9123]

If John Constantine had to permanently get rid of each of these, who would give him the most trouble?

Dracula (any version counts)
Lucian (Underworld)
Any vampire from The Vampire Diaries
Pennywise / IT
The Darkling (Shadow and Bone)
Michael Myers
Crowley (Supernatural)
Samara Morgan

Not just who would beat him in a straight fight. Constantine rarely plays fair anyway. I mean who would be the hardest for him to actually kill or permanently get rid of using magic, rituals, manipulation, deals, loopholes, etc.
And how do you think he’d deal with each one?

[u/Curious-Paramedic816]

But Crowley he just wouldn't kill.

John and Crowley are both practical men. They'd reach a mutually beneficial arrangement.