That obviously the best and strongest damane are most likely owned by the Imperial Family (like they have e.g. with the Ogier the best warriors). Since Tuon was the Heir of the Empress and leads the Return, which is basically a conquest, it makes sense that she took exceptional strong and able damane with her from Seanchan. On the other hand, Alivia was just one regular damane among many in the Seanchan army.

Therefore just common sense tells us that at least Sera - Tuon's strongest damane - is certainly stronger than Alivia, and possibly the strongest or second strongest female channeler on the "new list".