Physics.
I managed 100% and 97% in my chem modules last year. Basically, all you need to do is remember specific pieces of information. You rarely need to apply any theory. It's easy!
As for physics, it becomes easy, only once you have your head around the theory, and it never becomes easy unless your maths is up to speed. It's harder than chemistry is because of the problem solving aspects. In chem, you mostly regurgitate, or apply basic "laws" and rarely quantify. With physics, you're constantly applying theory and maths to solve problems. It's definitely harder, but also more fun!
I didn't do biology. I walked it at GCSE and it wasn't really my thing. From what I've seen of the textbook, and from the overlap with chemistry A level, it is easy-peasy. Rather than talking about enzymes and catalyasis in terms of molecular bonds, bond enthalpies/activation enthalpies etc. Biologists only go as far as saying "the reactant fits into the enzyme, like a lock fits into a key, hence it catalyses the reaction". Not a word of an explanation! Biology isn't a real science, and has more regurgitation than chemistry.
In my opinion it is as follows, from hardest to easiest:
physics>chemistry>biology
Although I am applying for a physics degree, so I may be biased!