Operative, called "Dental Hard Tissues" at our school, has been the funnest subject so far. Not only did we get lots of dental anatomy, but it was our first experience with prepping teeth, carving amalgam, doing composites, etc., etc.
Some of the hardest courses at my school have our Cardiopulmonary course, our Kidney/Urinary course, and our Pathology course.
I can tell you my least favorite lab so far...Removable Pros. Setting denture teeth is the most miserable thing I have ever done. My personal hell would be an endless line of occlusion rims that need teeth to be set. This is the only thing I have disliked in school so far.
My favorite might be implants. We just started learning it and practicing making stents etc and it's pretty damn cool!
I love anatomy...especially the dissection part....i hate "oral biology" where we have to learn all the odontogenesis, amelogenesis etc...they are darn boring..... don't know what this subject is called in US though...