I would say art, however I wouldn’t class it as “academic”. So, maths is my favourite. I love solving equations and the satisfaction of getting a hard question correct.
Seconded, math's been my favorite too, especially Calculus. Outside of traditional subjects, electronics and computer animation have been the most fun electives during undergrad. Grad school, mainly lab research since it's hands on (Mix of bioinformatics, biomedical/chemical engineering).
I studied computer games design at university. Lots of work but fun.
This included both research and practical assignments. One of them involved us creating a game that is based on and in the style of the TV series The Prisoner. We even got to go on a trip to Portmeirion which was great.
Brassica Prime:
Truly to be the most delicious is to wield this power. The power to create and destroy. And as the most delicious of gods, I am the font of this delicious power. From me spills all the deliciousness in creation.