Hi
My DD is at GSA, so can only speak for there, she has done Foundation in MT and about to start BA over on the acting side.
It is a fantastic college, part of the University, which has great facilities. I’m not sure how RCS is set up, but I felt that the campus was a really safe environment, everything on site, lots of social events, their own bar, supermarket etc.
I also liked that the students in halls are from other faculties, veterinary, engineering, sciences etc.
They guarantee halls on campus the first year, various types are available, but what DD loved was the dance classes in the evening at GSA, which are open to everyone, but a really reduced cost for students and the sports clubs.
Guildford is a small town within the commuter belt, London train well under an hour, trains back late, so going to the theatre is possible.
Your DD is obviously talented to get a place at both, I do however think GSA for acting, may carry more kudos within the industry.