Given our ability to exist in just one universe, the choice is not an alternate history versus present reality. It makes your framing odd. If you take the wrongful conviction as an axiom, the choice between death penalty and life imprisonment seems like an infinitely better improvement. If you can solve wrongful conviction (a separate issue that is much wider ranging that just the death penalty, given being barred from many lines of work and loss of one's right to vote after felony convictions, among other things) then that would obviously be better.
