In terms of sheer teaching quality (I was probably closest with my English and ex-Philosophy teachers personally), most likely my Literature teacher - he's the head of English at MGS, and I honestly believe the reason our school's English results are so good is because of him. Marking was often done in less than half an hour (I kid you not, in the third term holidays I would write essays, email them to him and he'd give them back within the half hour), and his knowledge of the texts were simply profound; halfway through the year, we found out that he'd lectured and completed part of a PhD at one of the Oxbridge schools, and we also knew all along that he was an Ivy League graduate (Pennyslvania).