Jean was stated in the 90s to be second to Xavier, however, that statement was never true. She was a constant joke whenever she and Exodus crossed paths. Shadow King, Stryfe, and Legion were also much more powerful than she (though they only showed up once every blue moon). Then you had Emma Frost who had much more impressive feats than Jean Grey, and then we also got Shaman X-Man, who was FAR stronger than Jean.
Jean is a joke compared to Emma without the Phoenix Force boosting her power or some other kind of external boost. As you can see in this thread, the Jean supporters only have rhetoric and feats where Jean's powers are boosted by the PF or by the addition of Betsy's TP. I have posted feat after feat for Emma clearly showing her to be FAR superior to Jean in every way when Jean is not being boosted by an external source of power.