The Federation is based off peace and exploration-Farms and research centers take less industry or whatever its called. All Federation starships are well rounded and can take a beating, they also have the longest range of ships. Diplomacy with Minor Nations that arent warlike is increased. Declaring War is Generally bad to the Federation.
The Federation Prefer to win By Diplomacy over any other option

The Klingons are a Warlike Race, as such, Double the standard Moral is gained from victory, no Moral is lost in Defeat, but triple is lost in a retreat. All Military Units are more powerful than any other unit, but are also weak in terms of shielding. On the Ground, The Klingons are incredibly deadly, only being rivaled by the Dominion. War For the Klingons is loved by its people, and everylong expansion is a must to keep public support.
The Klingons Prefer to fight to the very end, Retreating is always a bad idea.

The Romulan Tal Shiar is the best Intellegence system in the game, its Rival is the Obsidian Order under the Cardassians. The Romulans also have the best Cloaking Tech. Next to the Klingons, all romulan starships possess a cloaking device.
The Romulans Prefer to not fight head on, but bring down the infrastructure of enemy. This can be achieved in many ways

The Cardassians have the 2nd Most Efficient Military in the Game next to the Dominion of course. They have the Warships of the Klingons and the Intelligence of the Romulans, but they do not have supiorior in that sense. They Lack an efficient Science Department, but that is only a minor setback. The Cardassians are very Ruthless, and Garrison Forces can supress hatred from a conquered system. but not as efficent. The Cardassians, are essentially, a Second Place Empire, each of their assets can never surpass the group that holds the number 1 spot.

The Dominion are seemingly the Perfect Race, the Jem'Hadar can Supress and attack, their strength rivals the Klingons, Their Starships arent the Deadlist, in fact, they are pretty weak, but the Dominion can mass produce these starships. they can make as many as they want. Their Espionage will get what they want, but success varies, as most empires are on alert for changlings.