I only study Physics and Chemistry at A level so I can't say too much about Biology.
Although I enjoy physics a lot more, I find chemistry way easier. Chemistry is full of memorising information, a lot of which is fairly easy to grasp (especially physical, periodic table and energy). They give away so many free marks with all these moles/ratio/enthalpy questions whereas physics questions will leave you thinking for longer.
Not to sound blunt but chemistry really is a mark scheme subject like maths. Do a lot of questions and it's easy to learn and score well . Physics on the other hand requires a lot more skill. You can end up seeing some exam questions and have no idea what the examiner is looking for to get full marks on it.
Chemistry has the highest grade boundaries in science for a reason...
All great subjects anyways.