Except the fact that she was the female leader of the AS during the War of Shadow and a kind of antagonist of LTT.

I suggested in the past, though, that Egwene may very well be Eldrene ay Ellan ay Carlan Reborn, the last Queen of Manetheren.

It's indicated that Eldrene destroyed the attacking Shadowspawn army (and with it Manetheren) by using a very powerful sa'angreal. I believe that Eldrene actually used the female Choedan Kal. If this is right and Egwene is actually Eldrene Reborn, it would explain the scene in TSR, ch.11, when Egwene touches the female Choedan Kal access key in TAR and thinks that it strangely feels familiar:

"One thing actually seemed familiar, though she could not say why. Tucked into a comer of one of the cabinets, as if whoever put it there had been uncertain that it was worthy of display, lay the upper half of a broken figure carved from some shiny white stone, a woman holding a crystal sphere in one upraised hand, her face calm and dignified and full of wise authority. Whole, she would have been perhaps a foot tall. But why did she appear so familiar? She almost seemed to call to Egwene to pick her up."

Plus, in EotW, Egwene instinctively understands Mat's use of the Manetheren warcry:

"And we have a right, " Perrin added thoughtfully. "Moiraine says we're all descended from those Manetheren people. They fought the Dark One, and we're fighting the Dark One. That gives us a right."
Egwene sniffed as if to show what she thought of that. “I wasn't talking about that. What...what were shouting, Mat?"
Mat shrugged uncomfortably. "I don't remember." He stared at them defensively. "Well, I don't. It's all foggy. I don't know what it was, or where it came from, or what it means." He gave a self-deprecating laugh. "I don't suppose it means anything."
"I . . . I think it does," Egwene said slowly. "When you shouted, I thought - just for a minute - I thought I understood you. But it's all gone, now." She sighed and shook her head. "Perhaps you're right. Strange what you can imagine at a time like that, isn't it?"
"Carai an Caldazar," Moiraine said. They all twisted to stare at her. "Carai an Ellisande. Al Ellisande. For the honor of the Red Eagle. For the honor of the Rose of the Sun. The Rose of the Sun. The ancient warcry of Manetheren, and the warcry of its last king. Eldrene was called the Rose of the Sun." Moiraine's smile took in Egwene and Mat both, though her gaze may have rested a moment longer on him than on her. "The blood of Arad's line is still strong in the Two Rivers. The old blood still sings."

The old blood of Manetheren is obviously strong in Egwene.

Finally, even their first names sound a bit similar (a similar hint is also often used in the discussion if Elayne is Ilyena Reborn).

Others suggested that Egwene might be Corianin Nedeal Reborn, the last Dreamer before Egwene.

And again others consider that Egwene might be certain Amyrlin Reborn, especially the archetypical Green, Caraighan Maconar.