A general overview of Strategy Cards. The ones I'll review are the ones from the base game + the Imperial 2 card instead of the Imperial card. It seems that's the way a lot of people play (myself included), and it's my overview, I can do what I want =).
Initiative: A useful card. In addition to having your chocie of Strategy next round, it's the little things that make Initiative nice. You can do all those things that might not be worth a strategy on their own, but hey it's free. An action card here, some free trade goods there, and you get to go first (which can be a blessing or a curse). Initiative isn't really very fancy, but it's very useful. The only real drawback is a lack of a primary ability, so you can't use it to stall a turn, like you can with other strategies.
Diplomacy: Sigh. This card tends to acrue large amounts of bonus counters. It can be very difficult to judge other people's intentions. Diplomacy really doesnt foil too many plans. Usually if somebody really wants to attack, they'll get initiative and strike you before you can play Diplomacy. Or you will use the card on one player only to find yourself under a proxy attack by thier ally, or just some oppurtunist. The secondary ability is pretty decent, which further reduces my interest in taking this card myself.
Political: It just does a ton of things! Getting a command token back is helpful in its own right, if you were unable to get Logistics and need it or something, it can keep you going a bit longer. Action cards are always useful, as is toying with the political ajenda. Political strategy takes a bit of timing to execute, as you want to use it when you have lots of influence and nobody else does. This means a lot of stalling for turns, which some races, like Yssiril or Sol can do easily, but is not quite so easy for others. Still, if you have action cards to play, that can help.
Logistics: To me, this is like the strangest card in the game. Everybody ultimately needs command counters, but actually taking the card is kind of a last-ditch, no other options kind of thing. The reason for this is that early game, Logistics isn't really needed much, and it's preferable to choose strategies that will help you expand or build. Late game you can often get more than 4 command counters simply by activating the secondary of Logistics when somebody else finds themselves forced to take it. That leaves like a few rounds in the middle when the card is actually at it's prime, and even then it's only mediocre.
Trade: I find Trade to be quite good, extra resources are always a plus, especially if you have trade agreements set up. 3 trade goods might not seem like much difference, but since trade goods are so versitle, it's much better. Trade goods can really help out when trying to fufil objective cards like "I now spend 10 resources" or something. Whether it's for bribing other players to vote your way on political adjendas or just buying up extra ships, trade goods are always welcome on my race sheet. The b) option is a little less useful, IMO, the only real reason I could see for it would be if you have two opponents allied against you with strong trade agreements, or if you think that Hacan just is getting too good of a deal. Still, ultimately, this option only delays your opponents a turn or so before the trade agreement is re-established.
Warfare: This is one of my favorite cards. An awesome primary ability and a very crappy secondary? Sign me up. Fantastic for quick-expansion in the early game, for getting fleets through holes in the enemy defense grid, building extra units at a space dock, or giving your fleets a bit of movement and tactical flexibility. Plus, like political, you get a command counter out of it. Usually you'll spend it again next turn, but you don't have to. Warfare lets you do more stuff, and that's where it's all about. On the secondary side of things, I haven't found much use for cruiser/destroyer patrols. The restrictions are a bit harsh, and I don't find it worth a strategy token. If anybody has had sucess with these, please speak up.
Technology: Ok, I'm a tech sucker. I admit it, I tech too much. Sue me. Probably this is because I can't roll dice, so any extra +1s or little bonuses are well needed. There are just so many fun things to do with technology, PDS defense grids, type4 drives, integrated economy. ... they're lots of fun. I find this strategy especially useful early-game when your opponents dont have the resources to use the secondary, you can get a tech advantage. Late game it's still useful, activating it early makes your oppoents choose between advancing in tech or saving their resources for ships/ political votes.
Imperial2: Probably my favorite card in the world, I actually sleep with it under my pillow =p. Points are good, so Imperial Throne is amazing if you can play it. But even if you were going to play it and somebody else hijacked Mecatol Rex away from you before you had a chance, you can still use Rapid Mobilization, build a fleet and later move with the same fleet to try to get your planet back. Rapid Mobilization is rediculously useful *all* the time because moving with fleets that you've just produced is just plain good. Okay? It's good.