My personal experience and experiences of those who I've talked to, as well as some common sense, and for this instance I'll stick to the educational environment of California in the sciences. There is a stigma that professors at CC's are from po-dunk schools where they earned their bachelors or masters and then just went into teaching, and this is very often incorrect. My Physics professor had his PhD from Yale and wrote the book for the class, my Gchem professor had his PhD from MIT, another Chem professor from Caltech, the list goes on.
I can say from my experience that the vast majority of science professors which I've had at the Community College (Cypress College) have been hands down better than my University professors (UC, Irvine). A number of factors go into this - the major difference is that the vast majority of big CA schools are research schools, UCI, UCLA, UCB, Stanford, etc. Because of this, the schools higher researchers, not teachers. While some of these professors may very well be one of the foremost experts in the field, and I've taken a number who are, they often have a horrible time trying to explain it clearly to others in a way which they can understand and master the material themselves. For many professors you can tell that teaching is a complete afterthought to doing their research, some only teach their one or two classes a year which I'm guessing is a minimum requirement. Some of the professors I've had simply put up the power point slides that come with the book and read directly off of them, giving the lecture absolutely no value, and requiring the student to do extra work to full grasp the material. On the other hand, the only reason to be at a Community College is because they have a desire to teach, and while desire might not equate to teaching skill, you can tell that it's what they're there to do. A number of my professors worked in industry for the majority of their lives, chemical engineers, pharm, etc, and they made plenty of money doing that, and now that they're either retired or left the industry, they want to teach. These are the professors which I've found are often the most inspired, and strive to do their best to foster student understanding.
Another factor not directly related to a professor's teaching ability but which does greatly impact the student's learning experience is class size. My Organic Chemistry class had 14 people in it and was done in a small seminar room, the same class at UCI has 400, and is done in a movie theater size lecture hall. I'd ask you to guess which has more student/teacher interaction, and ability to understand where students are struggling? This is the same for biology and physics classes, and this isn't just an issue at UCI. Of course a counter argument to this is saying that office hours are available, but with 400 students, is 2 hours a week really enough? I also know that there are classes taught by TA's, completely removing the "professor" from the class room.
Now please don't take my argument to mean that you won't get an excellent education at a big university, or that ALL university professors are bad, this is definitely not true. I have had a few amazing and inspiring professors at the university level, but it is a stroke of cosmic luck to find such professors who are both at the top of their field and amazing instructors. Dr. Francisco Ayala at UCI is one of the foremost evolutionary biologists in the world, and I can say he was not only inspiring but deeply thought provoking, and had a strong desire to get his students to really think about the topics, and promote student interaction. Also, one of the biggest benifits of being at a research university is the opportunity to do research, which you can't get at many other schools - just about every other bio major at UCI has or is doing research, and the other half is either not interested or hasn't tried very hard to find a research lab.
And also remember that this is referring to sciences, especially since student doctor is for pre-health professions, and thus most of the readers here will be science majors. I really have no qualms with saying that big universities have amazing non-science instructors, as most of the ones I've had have been great, as have the majority of non-science CC instructors I've had.
I hope this clears up my point for you.
