Do check out the syllabus for RS for the board that your daughter's school uses. My son was very keen to do RS because he loved the philosophy he had been doing in RS classes in Years 7, 8 and 9. It turned out that there was little in the syllabus for the board his school was doing and so he decided to do Geography instead. He was told that if he wanted to do RS A Level ( which contained a lot of philosophy in the 6th form )the school would consider allowing him to do it without RS at GCSE.
Please also consider the geography course and the specification and the topics the school are likely to be studying and discuss with your child whether they will enjoy them. Also consider the practical aspects and the skills required.
I also understand one of the core subjects is English and I therefore presume this is English language and there is no English literature ?
Certainly at A level both Geography and RS are well regarded.
At GCSE neither can be considered to be a "soft" subject.From the exam results of websites of a number of schools it appears to me and it is a generalisation easier to get top grades in RS as compared to Geography although both seem to get many.