I’m going with math because I always struggled with it. Art because I’m not artistically talented, and gym because, well, it was gym.
So visiting France with the kids ..
..then current wife had French to post grad level
…daughter and son in private school with French each year
…asking directions??? ME!!! ALWAYS!!!
Fractured French acquired from the back of product packaging, 
I swear my family members were too embarrassed to try their Canadian French and left it to me…however they at least provided translation of the replies I got. 
Now of course we were in the south a lot and Provencal version was I’m told closer to Quebec version.
That heaping plate of escargot in gravy in a southern France eatery made it all worth while… 
My wife learned French as a student spending a year in Paris (after majoring in French in college) and when we moved to Montreal has never had any problem communicating with Quebecois. They certainly understand Parisian French and nearly always can speak so she understands.
I hated gym class. I was overweight and unatletic. I never into sports growing up, not even as a spectator. I went to exactly one pro baseball game as a kid, got bored, and never looked up once after I got a book out of my backpack. Gym was compulsory every year except 11th grade (we had heath instead). The older I got the more I hated gym. In HS I still hadn’t grasped the basics of sports like football or basketball ball (the default activities for boys) and never overcame my instinct to flinch & get out of yhe way whenever a ball came anywhere near me. I actually prefered stull like calisthenics, aerobics, even weightlifting, but rarely did those.
Also I’m gay, which led to other issues. Ironically I never had an issue with lockerrooms, that part of class I liked and kinda wished the district still enforced showering. But in class itself anything that involved close contact, especially physical contact, with other boys was pure psychological torture. Try holding someone elses feet and keeping count while he does sit-ups when you keep getting distracted by how close his crotch is to your face, his bulge, glimpses of his treasure trail as his shirt moves, and most of all his musk. I’m still not into sports, but ironically have a major jock fetish.
I took three years of German, mainly because I have so many German family members, but I hated the class because of the teacher. And the main reason I hated her is that after every test she would reseat the class in the order of how they did on the test…first place in the upper left seat (from the back), then fill out that column, then to the top of the next column, and so on.
That was mean for everybody, and it made for tension after every exam was returned. And on top of that, the thing is, I was almost always second, but in my senior year I went through a really rough period of depression, and across half a year I inexorably drifted back in the class toward the back or back/right, and you know, that’s not only visible to everyone, but it made me feel so much worse. I mean, that was more than 40 years ago, and I still feel that one.
Honestly, the people who become teachers.
I hated most subjects, most of the time! I think the worst was maths because I really didn’t understand much beyond the basics, and at the time we had a Bangladeshi teacher who had such a strong accent, I had trouble understanding what he was saying and therefore even more trouble following his mathematical workings out.
I’m more of an arts person so I loved English, creative writing, music and history but was absolutely abysmal at art itself. I can’t even draw a stick figure with the help of a ruler! I wasn’t great at sciences either, we had to take physics, chemistry and biology until it got to time to pick our options, and I chose biology because it’s the one I was the least bad at.
Astronomy
It was an elective. I had some interest in planets and knew the North star.
The joke was on me. It was a tough class with a lot of physics and math. I worked my butt off for a B.
Despite being a voracious reader who lived in the library as a kid, the subject that I despised the most was English. I couldn’t wrap my head around the rules. To this day, I couldn’t diagram a sentence if my life depended on it. I don’t recall ever doing well in an English class.
These days, although I spend my nights working as a professional musician, I supplement my income during the day as a paid writer. Life is funny sometimes.
Spelling, just completely lacked the skill; although an excellent reader.
Strangely later in life, it just came to me one day; at least at an intermediate level.
The brain is a weird thing.
Mechanics. One problem in particular was especially fearsome:
Imagine a model of the Earth as an oblate spheroid of uniform density. Now, as a different model, imagine the Earth as a sphere of uniform density with an additional thin layer of positive or negative mass-per-area on its surface. Describe the difference in gravitational field intensity between these two models, as a function of location in space.
I hated English class, but always found it to be an easy A. Of course I hated school in general, whether the class was hard or easy.