Having done 1 and 2 PE last year and 3 and 4 Legal this year, PE is the better subject by far.
Legal is extremely repetitive, learning a concept, being able to describe it, then being able to evaluate it. The topics are also very very bland and boring, Eg. The constitution and Parliament, and the course contains none of the criminal law studied in year 11. Your teacher is barely required, as they just set readings and textbook questions
I cannot speak highly enough about PE though. Very interesting, and if you are a keen sportsperson, every concept you learn applies to sport in one way or another! It does overlap with some science, but not in great detail.
My advice is to go with your passion! If you are a sporty person, or have an interest in the human body, PE is the one for you. If you watch crime thrillers (unfortunately legal isnt nearly as exciting) and like to keep up to date with current affairs, I would choose legal