Thanks to a lack of cash, I don't own DA or TOA. The following was played on the original GalCiv 2.
I play on "Tough", so this may not work for you Masochistic/Suicidal types (in fact, it probably won't).
I'm four years into my current game (Huge galaxy, common everything, loose clusters) as the Iconians with my preferred picks, and I'm completely dominating the AIs (Drengin, Korx, Yor, Arceans, Thalans). I could crush any of them but the Arceans at will, and the only reason that I can't instantly wipe out the Arceans is that it would take a while to absorb their 42 planets (nearly as many as me). I'm making well over 600 bc a turn, and my treasury, even after a fleet-wide upgrade that cost almost 50000 bc, is larger then all the AIs combined. Any individual one of my ships has more attack/defense then the strongest AI fleet. My manufacturing and research both outclass the Arceans, who have more advanced factories and labs, and I have researched every diplomatic technology in the game. Basically, I see no way I can possibly lose this game.
I don't consider myself anything near an expert player. I also don't think I'm ready to move on to the next difficulty, judging from my last game, in which I am almost certainly going to be obliterated by the gigantic Torian empire. Yet in this and in my previous game (with very different settings) as the "weak" Iconians, I have won with far more ease then with any other civilization. I'd welcome some speculation on the reasons for this.
My picks for the Iconians
4 points Economics (+30)
2 points Diplomacy (+10)
1 point each Social and Military production (+10)
Political party: Technologists (+20 research, +1 sensors)
My goal is to turn the Iconians into a research and economic powerhouse, taking advantage of their default +20 to research and impressive number of starting techs. The diplomacy points are so I can swindle the AIs at tech trading by trading them techs they (over)value in exchange for everything they own. Social and military points help round them out. I've noticed that the combination of +30 economics and Xeno Economics as a starting tech means that I can almost completely avoid the early post-colony rush economic collapse.