Great topic JD, I keep having conversations with a friend of mine about Lordi's voice, and was curious when someone would open a topic like this!
Definately Deadache for me! His vocals got really darker at this point, and a lot more gruntier and raspier, a huge improvement since Get Heavy. Huge kudos to him for singing so well live now, his voice has really gotten more darker and sinister these past couple of years. I can only hope he will continue singing in this manner, with an occasional soft, creepy whisper like in "Monsters Keep Me Company" or the beginning of "Man Skin Boots". But the way he is singing right now is perfect for me, after all, Lordi is my personal favorite vocalist, and like fine wine, he gets better at it with age.
And of course, huge kudos to the three things that make this all possible:
Chocolate
Cigarretes
Pepsi

Actually I'm a Plumber.