I'm torn. I had 2 favorites.
My second first grade teacher was great because she was smart and compassionate. We moved from West Texas to Oregon in the middle of the school year. I had a horrible time in the reading circle. I remember holding my hand on the word "is" and saying it to myself over and over again, just in case I needed to distinguish it from "it." My teacher, Mrs. Young, originally thought I was just a poor student, until she looked over my math scores. I was at the top of the class and pushing the envelope on math. Not such a dummy, after all, she asked my parents if she could tutor me after class. Silly me, at the time I thought I was being punished. I didn't appreciate the gift. Years later, when my first novel was published, I sent her an autographed copy with my thanks.
My 11th grade World History teacher, Mrs. Hendry, was delightful. She was wisdom incarnate and brought history to life like no other. She hated the memorization of dates just for the sake of memorization. She did let us know that we would have to know some dates, but that the key to history was not dates, but motivation. I was hooked! I could feel the truth of that in my bones.