Chemistry is the hardest, it would be far too hard for me. I barely got out of A-level Chemistry, I couldn't have kept it up at University level I imagine. I think hard subjects are just hard across the board, regardless of institution because of the sheer volume of what you have to learn to reach even a basic level of knowledge.
Easiest is a bit of a tricky one, because I think it depends purely on where you go. For example, I know some places that do business studies can go pretty easy on the students and it's not too hard to get a degree because you don't have to learn so much. But the same subject at a high profile business school such as the London school of economics would be extremely hard because they expect much higher standards and you are required to learn much more.
