most of the time with ventress the reason she survived so long was because she was a coward so saying her surviving fights cant really be used
but i do think she is a better duellist but bastila is extremely skilled in the force ( i think the youngest jedi to of mastered battle meditation (something was not seen in any of the films.))
Ventress coward? not realy what porpuse would serve to fight to the death if there is none to gain?!
But she nearly killed anakin and Obi wan combined if was not from dookus betrayal, she had them with force choke both of them.
she run away alot of times yeah mostly when surrounded and against odds , but the fact that she did get away proves that she is much more skiled then one might think. Also she was sucessfull many times in the service of the Count Ventress run away from Unduli and Ashoka, but she got what she had came for, the Vice roy who was their prisioner.
Basttila well she was a prodigal with great potencial just like jeasa is in swtor, but thats much about it. Not saying she wast skilled at all, for all i know she could well beat ventress but given of what its kowned about the two, i think its unlikely.
I realy enjoy ventress as a character particulary now that she is on her own.