RockTheCazbah87
Pacal's pal
Her history is kinda sketchy and tied up in the politics of Roman historians. She led a rebellion of British Celtic tribes starting with her tribe, the Iceni. She isn't associated with mainland Gaul at all. From a gender inclusion perspective, she's pretty cool. From a representation of all Celts, she fails quite a bit (the Iceni represent the area around Colchester). Vercingetorix gets all the mainland Gaul. Then again, Boudica might have a better military record than he does.
In the end, I'd say it's a toss up between the two with Brennus being third.
As ignorant as it may be, I'd never heard of Brennus before Warlords, whereas I was more well-versed of Boudica and Vercingetorix's exploits. 'Big V' would definitely get my vote for inclusion, should the opportunity once more arise.