It doesn't really matter, as far as the gameplay is concerned. You might get a different ending depending on who you take and who dies. When you talk to Zulu a list of names will appear in the dialog, those are the ones you can go get. I know you can get Noah, Stryker, the military guy in the scientists bunker and that guy who owes money in the Duty/Freedom base. There might be more depending on what decisions you make during the game. Like, I joined the bandits so I couldn't get Noah.