Our diversity makes us stronger. Non-Terran citizens of the Free Union are treated as equals to the Terrans. Although some societal prejudice and xenophobia does exist, it is the exception rather than the rule. Among spacefarers, who regularly encounter aliens, xenophobia is rare.
The crushing authoritarianism of the Ascendancy is an affront to the dignity of their citizens. The Free Union was fortunate to be able to escape their grasp, but they are still one of the most powerful entities in Known Space, and must be, if not respected, at least feared. Individual Terrans might be honourable and useful, but beware that an Ascendancy friend might be ordered to betray you at any time.
Honourable and driven, but their strange religion and drive towards total competitiveness can make them unpredictable and dangerous. The Dominion as a whole does seem to have a certain respect for the people of the Free Union, but wars have broken out between the two factions on multiple occasions in the past 500 years. Their traders are generally fairly reliable as long as you don't provoke them into a “challenge”.
Too patronising by far. The strange powers of the Elysians make dealing with the Commonality a risk. However, they seem to prefer dealing with the Free Union over the Ascendancy, and do seem willing to assist and trade with Free Union colonies from time to time. They seem to have an interest in what explorers can discover in space most distant to their own, and place a high value on such knowledge.