Has Bastila gone toe to toe with two of the most powerful Jedi ever? Can Bastila keep up with most of the PT Jedi Council members?
She never had the chance. Argument = fail.
Given the dubiously canon nature of many of Ventress's 'OMG' moments, there's no doubt in this match-up. Bastilla Shan may have had a primary function leaning toward directing large groups with her battle meditation but her role in the events following Revan's adventures shows that she is vastly more experienced in Force lore and lightsaber combat,
The Clone Wars cartoon may paint Asaji Ventress in a favorable light but her skills are rudimentary at best and she has no discipline or deep Force connection.
And Bastila never went on to show her true potential, as she settled down with Revan later on. As I've already said, she is the kind of character who rises to the occasion. We've never seen the true extent of her potetial, which was no doubt vastly superior to that of Ventress.