I really enjoyed the microbiology, but my interests lie in chemistry and applied science. I found A&P I a completely tedious bore. My school split the A and the P parts, and the I class was just a lot of rote memorization and drill. The physiology was more interesting, because there was more "action" in it, like how the body's systems work. Still, micro was far more interesting and thus easier and more fun to do. I enjoy research, and patho, though.
Also, there are different levels of difficulty, regarding those micro classes. Some colleges have everything but the kitchen sink in theirs, because the same class is used for pre-med, etc., and it's very demanding. Some schools make you do a lot of patho work, and extra work outside of class, and some don't. You might want to shop around and see is the actual content your school and at nearby colleges, too, especially if you are just racking up prerequisites and they can be from any school.