Gotta disagree with Willy about the Yor's weaknesses including economy....their passive economic bonuses rock because  they don't use up any planetary tiles the way that econ building do, meaning more research and/or production per planet.  Plus they get the efficiency centre, and the maintenance grid, which helps you keep tax, and therefore cash, high.And if you do trade for or steal tech that allows you to build trade centres or stock markets and/or morale buildings, then it is seriously ker-CHING! time; more money than you can spend, especially if you get an economic boom event. The weaknesses for the Yor are influence and diplomacy, though the influence thing is kind of a double edged sword...they can't really exert enough influence to flip anyone, but their 100% loyalty bonus means they are freaking tough to flip too, allowing you to take planets deep inside other races influence zones with little chance of them switching over