Not sure why going to a college which does not use TAs is necessarily better for this situation. If there are two instructors (faculty and TA) teaching the course, the odds of at least one being understandable in terms of English dialect or accent is better than if there is just one instructor (faculty, no TA). Student / faculty ratio or class size may not have much of an effect, since if the instructor’s English dialect or accent is difficult to understand, it does not matter if one is listening in a large lecture hall or a small classroom.