For me it was maths, but I know that a lot of people would strongly disagree on that. The "easiness" of a subject is very much dependent on who you ask. I struggled to get a good mark in English Lit, but other people breezed through it.
Well I would say maths but I did better by percent UMS in all 3 sciences (all 4 A*).
I'm definitely better at maths than physics though (in AS level +)
So, I'm not sure whether to say science because I did better or maths because it probably is easier.
With RE I did well on the exams that I remembered the content for and did badly on the one I didn't.
It completely depends on the person as loads of people have said but for me personally [I got 8 a stars and 5 as at GCSE] it was definitely ICT. A massive bunch of the course was easy peasy coursework then the exam I paid no attention in any class, didn't bother at ALL but managed to get 100% in the exam with just a couple hours of revision the day before.
not sure if I was lucky but that's how it worked out.English language was also really easy due to a load of waffle and a few quotes being considered a good exam essay technique... Though I think the standard of GCSEs is rubbish, I did mine in summer 2010 and the teachers and school go out of their way to keep the school's stats up.