Well, here it is. The place for it. How do you play Alpha Centari?
Myself, I prefer rushing a population boom and sky farms, and running the tech/money boom one can generate off of cities with populations of 30 or higher.
I go as Deidre and tame worms to harass that damned Miriam while I build up tech and diplomacy with Santiago, and us Pact Sisters rule the world, before I end up pitting me and my worms against her. On the hardest difficulties, even my planet busters can't save me. It always comes down to the last two cities, the rest being nuked (Sometimes by me >.>) and cranking out soldiers to harass the other. It's such a fun game.
I like to use Lady Deirdre too and take advantage of terraforming bonuses making land management the foundation to my strategem. The Professor is a very good choice too if you race and get the tech to make you bases immune to spies, with that weakness handled the high tech units are always worth handfuls of the enemies units if you play a fast aggressive game with them before the last ones standing are all at even tech, that's when you realease those stockpiled nikes you built thanks to not needing as many units as the other team. The Hive is great too, not having to deal with unhappy citizens is like a relief from a major drag that can slow down other factions if they don't get a handle on their crowds (zap!). Early strong base defences ensures that they'll survive well through the initial development of their landing making a strong foundation to work with in the mid-game. The final one I also like to use is the UN Peacekeepers. Population advantage here hands down and an almost sure fire guarantee to be planetery governor otherwise you are on a random map with a horrible random start or you are doing it wrong.
I go with the Peacekeepers, controlling the Council and politics goes a long way in my mind, then instead of destroying other groups, you subjugate them, then give them back their territories and cities, so they can become powerful again, only as a puppet nation to the Peacekeepers.
However if I'm playing with the expansion I play pirates, sweet talk my way around the planet and then raise the sea levels. Even pirate land bases come with the a pressure dome, so my bases stay dry and nice, everyone elses sink.
Saint Del is considered a holy healer of diseases of children, but also as a protector of cattle.
I'm usually a Deidre or Zakharov fan, due to capturing worms and rampaging over everyone with them or out-teching and bombing everyone into dust. Aircraft rule.
Though, in smaller maps, I prefer Miriam for sheer offensive power. I'm convinced that she's better at it than Santiago at all but the highest difficulties where the prototype costs really start to be a pain.
Yes Miriam is a pain and if she and her ilk are left to live when all the factions have evened out at the top tech she'll be the force to reckon with. Santiago is one that has to be played quickly and aggressive while you maintain an advantage that is almost negligible at the end, I find.
Early game, free captured mindworms, you can crush your nearest neighbor with them, and once they've gained veterancy from larvae to boil/mature boil, crush the second one. As far as I know, you dont need to support them either.
As Deidre also, you can use your social projects to gain +6 efficiency (at support expense of -1 support, -1 police and +4 environment) [Democratic,Green]. Spam bases, you can support up to 30 with +6 eff without extra drones. Build loads of bases on the seaside, then spam boreholes and farms/solars at those bases to make your awesome trained silksteel missile destroyers.
Retain enough credits to bring some of your previous units, likely synth sentinels and plasma sentinels, up to par, and begin your offense when you reach gattling laser (5 attack) or missile tech (6 attack) (whichever comes first really).
Once you reach this phase, switch your Democratic policy to Police State (+6 eff -> +2 eff, -1 support -> +1 support, -1 police -> +1 police) if you need minerals due to the crappy support costs. You might have to nerve staple a lot of places as I did, but Unseelie suggested to me to cut down on economy and labs in favour of psych, which in hindsight was probably better. This allows you more or less +4 minerals at each of your production bases, which should have in the area of 12-25 minerals after deductions, allowing you to spam destroyers, destroyer transports, foils and various other implements of increasing pain.
At this point I made the mistake of having upwards of 35 bases, which was basically a third of the map, a whole continent, of my bases. Except Lal, who was a protectorate and who held the bottom of the island.