Most: Burnt to death
Least: Lethal injection
That's my own opinion

Least a bullet to the head, you don't have time to feel anything. That's how I'd do it

Most: slowly bleeding out
Least: drowning. Drowning doesn't hurt as much as most other deaths

Drowning is painful tho

How? Sure at first but then your brain shuts down

Because trust me, having you lungs filled with water is painful

Yeah but then u go numb. Sure, dying fast is great, but you'll be in pain the split second before you die.

It takes time to drown

Yea. Agree to disagree? This isn't really going anywhere and its a matter of opinion

And drowning is like suffocating

Bullet in the head is definitely the least painful.
Bleeding to death the most.

No, @creativedragonbaby drowning is incredibly painful. I would say that's one of the WORST ways to die. I've almost drowned twice and firstly, you're body goes into shock and you panic because all you want is safety and air and so you struggle then eventually when you do need to take a breath you take in water, it fills your lungs and hurts a fuck ton cause your lungs are trying to push it out but you're sucking more in so your chest feels like a rocks being smashed into it. Then you slowly black out.
So for me, least painful is lethal injection.
Most, is drowning in oil or flaying