... then Egwene definitely commits the higher atrocity. Aes Sedai slaves of the Seanchan wouldn't add any more numbers to their military might (due to the Three Oaths). The only advantage is the knowledge of Traveling. If you think about it, this was an inevitability, since Elaida positioned herself at the top of the Tower, where the Seanchan raid originated. Egwene should have deduced this, imho.

Her actions were motivated by her own opinion of being on the bad end of forced slavery. Better to be dead than that. Though many of the Aes Sedai may have chosen this option, it was made for them, and Egwene isn't much better than the Seanchan for this choice. As it could have been, those Aes Sedai might have been negotiated out of their bondage at a later time. Now, they're just dead.

Her actions were very rash, especially when considering the fact that she had a Dream of needing the Seanchan for salvation right after the one about the Tower attack. This should have given her enough insight to at least understand that she is dealing with a misguided people who are not evil and can therefore be negotiated with.

However, Rand still takes the cake in this book. Not for your example, but for abandoning the people of Bandar Eban to starvation. That was a hard scene to take in, and I think it was a much darker choice for Rand than balefiring a bunch of overCompulsed sex slaves.