I don't find the fact that some people are found innocent to be a convincing reason to be against the death penalty. The replacement, which is life in prison, strikes me as even less appealing. How is sending someone to jail and leaving them there for 20 years only to figure out that people fucked up and the guy wasn't actually guilty - "Sorry chap, but it's only a third of your life we've ripped away from you, you'v…
What if it was you? What if you were framed for a crime? Would you prefer the death penalty then or only if it's someone else's head on the line? State murder is an ugly business that has no part in any modern society.
I'd consider being in long-term or life prison to be the next closest thing to those examples; a life without freedom, friends, family, with the potential for a wide variety of suffering beyond that - poor medical, poor food, guard abuse, fights, solitary, rape - what in this is worth living for? Prison is specifically meant to be a punishment, not a rehabilitation. And then maybe you get out a couple decades later, everything has changed, no one will hire you, everyone has moved on...