11th grade was hard but I think that's when I developed the most as a person and I had good study habits, so that was the best. As for my worst, 8th grade was horrid. No friends, bullying, bad grades, teachers hated me.
My worst year of school was 6th or 7th grade. I hit puberty then and had moved to a new district. I was also probably the only minority at the new school so I didn't fit in. Not fun.