Well I have a lvl 22 Biological which I just beat the game with, and I got Lvl 19 Death Sentence from the Mayor.I am currently using Emerald Death from the Hydra boss in Zone 4.
The stats given from both are as follows:
Emerald Death: Strength +186, Vitality +34
Death Sentence: Strength +152, Vitality +66, Speed +66
the large speed increase should make up the strength lost from emerald death, and of course death sentence gives more vitality, so i say death sentence
Depends what you play. If you're a Predator Form/Destroy bio, Emerald is good. If you're speed, then Death Sentence is better. If you're toxic, neither, since none of them have poison piercing.
I would have to say that Death Sentence is better than Emerald Death since the lack of strength from Emerald Death is replaced by higher vitality,and lots of speed