Teresa was indeed strongest in almost every way, except for maybe the most important part if you want to be a surviving claymore, which is heartlessness.
Yet Im glad she died because of what she chose to become, rather than losing in a real contest of strength. If she had any regrets, it would probably be leaving clare alone, for I think she would not regret learning compassion even if it did cost her life.
The other claymores were just really weak. Teresa and Priscilla were on a class of their own. I wonder if Clare will ever reach such a level. Is the present storyline a story of revenge then?