<p>Personally, I like having professors teaching lectures and TA’s teaching labs and recitations. It gives you the chance of two teaching methods, two interpretations, etc. I have had classes where the professor was rather opaque and incomprehensible, but the TA was clear and helpful. In other classes, they simply complemented each other, each one able to offer insights in different areas. At a good school, the TA’s are rarely anything but knowledgable and (as others have noted) often much closer to the problems of the undergrads.</p>
<p>Of course, I have also had courses where the two were in lockstep in mediocrity, but a solid chance is a lot better than nothing.</p>