There are too many issues with the death penalty that I can't agree with it.
Jails are bloody expensive. On the one hand, you could kill off the worst criminals so they don't have to live in jail and eat tax dollars. On the other, smarter hand, why kill a handful of criminals when there is a plethora of low-risk offenders that you could release?
Also, the tax dollars spent on prison guard salaries could be better spent on workers who can help rehabilitate prisoners and help integrate them back into society, preventing them from being sent back to prison, which means less prison guards are needed, which means prisons will slowly become cheaper over time.
The highest risk offenders, including the ones that would be sent to Death Row, could just be housed in what regular prisons are now.
Also, in a perfect system there would be no citizens falsely incarcerated, but it happens, and to have someone on Death Row killed for a crime they didn't commit is not a risk I'm willing to take.
The more I think about it, the less I can rationalize the death penalty. There are a ton of better options.