Sweeney.
The problem with Cerberus is -- well, there are a lot of problems with Cerberus, actually. Too many to name. They call themselves a human survivalist group but what they don't tell you is that they don't give a shit about the rest of the galaxy.
And yes, even before that. His people wanted to put a control implant in my brain, to make sure I'd be compliant. And I told him to get lost only after he got angry at me for destroying a Human-Reaper larva.