I did biology and psychology at AS and found psychology to be a hell of a lot easier even though there seemed to be much more information to recall. I know people who did psychology/biology/chemistry and out of those, they found the hardest to be chemistry and I know someone who did psychology/history and dropped history.
I don't know anyone who did RE but from my experiences, it seems people think psychology is one of the easier/more enjoyable courses. Of course, it's ultimately down to you and what you enjoy since ease is subjective (+ subjects seem easier if you enjoy them)