Etranger: The 2300 (or Twilight 2300) SF RPG setting does indeed have “space french”, and they are a dominant force, having colonized at least 1 arm of solar systems. Of course, the 2300 setting has it’s bad guys, in the for of the Kaffer aliens, but before they arrive it is a very byzentine setting.
I ‘m with Rhoderic: the HG and JC settings are fantastic. Though in both you are sort of led to believe that there are certain bad guys (Earth in both settings, and the SDR particularly in HG) and good guys (Jupiter in JC and the North and independent badlanders in HG) the very deep political, social, and racial fluff gives a much deeper sense of the world (as it was designed for roleplay before table top) than most settings can come close to.
"I saw this in a cartoon once, but I'm pretty sure I can do it..."