Definitely the easiest possible setting. I'm not well experienced in this specific type of game (just Civ type games) and there's a lot of information to take on board. Once I pull a couple of victories on the easiest, I will move up to whatever the next is called. I doubt I will ever go up past Normal (intelligent) as I tend to find with most games that I can scrape wins on the harder difficulties but gain a lot less pleasure due to excess stress!
For example, I can beat Civ4 on Monarch - I even did it once on Deity.... but there's just no pleasure in it for me, it's all min-maxing and purposefully chosing to neglect many areas of the game to focus on an all out strategy. I vastly prefer to play at Noble and relax throughout the game, build cities where I want to, build up all my cities etc. This, I am sure, is how I will want to play GalCiv2... fighting wars to gain the best planets then building them up, specialising them, "completing" them all before making a final armada to crush my enemies.
Not knocking people who like this kind of thing (uberness), but I play purely for pleasure, not to prove I am good! A reason you wont be seeing me on the Metaverse.