I wouldn't say they're the necessarily the best, but they're not necessarily worse than the other nations of the Westlands. In some cases they're better, though that depends on a nation-by-nation basis. An commonmer of Andor might be better off than a Seanchan commoner, but that Seanchan commoner probably has it better than a Tairen one. On one hand they have slavery and a fairly rigid class structure, but on the other, there is the opportunity for advancement through meritous deeds. People may fear crossing the Blood, and the Seanchan are harsh against those who oppose their rule, but the Tinkers feel safe in the lands controlled by the Seanchan.

Our early view of the Seanchan was shaped by characters like Suroth and Renna. Suroth is a Darkfriend, and Renna was nothing but a cowardly bully. But compare them with people like Tuon, Egeanin, Karede, or Tylee and there's a great deal of difference. I think it's to RJ's credit that instead of making the Seanchan simply some monolithic evil empire he portrayed them as a more complex society.