I would solicit bids from the two groups. I imagine that the 3^^^3 people would be able to pay more to save their lives than the 1 person would be able to pay to avoid infinite torture. Plus, once I make the decision, if I sentence the 1 person to infinite torture I only have to worry about their friends/family and I have 3^^^3 allies who will help defend me against retribution. Otherwise, the situation is reversed and I think its likely I'll be murdered or imprisoned if I kill that many people. Of course, if the scenario is different, like the 3^^^3 people are in a different galaxy (not that that many people could fit in a galaxy) and the 1 person is my wife, I'll definitely wipe out all those assholes to save my wife. I'd even let them all suffer infinite torture just to keep my wife from experiencing a dust speck in her eye. It is valentine's day after all!