Kane can flat out score but isn't that effective vs the big teams, Rashford has already shown he's class vs tough oppositions such as Chelsea and City.
Kane is a top class finisher however, that's all he can Do, whilst Rashford's finishing isn't fantastic it's something I know he will develop. He is also way better than Kane at dribbling, affecting play outside of goals, playing in alternate positions too, way more versatile in every other area of his game already at 19.
Whilst Kane is top class at what he does, top 10 in the world for sure, Rashford is more versatile and has the potential to be better than Kane, we do have to understand there is a possibility of Kane improving in other areas too however, I don't think he will, I actually don't think it makes sense for him to either, he's class at what he does and try be the best in the world at it. Rashford all day for me.