I think, apart from many the very remote chance of a disgruntled parent at either school, you're likely to hear good things on both.
I had a DD at one and DS elsewhere but knew friends at the other.
Both really good schools, one has a strong Aademic reputation as its USP, the other has Pastoral Care and value add. GHS being the former and Tormead the latter. Tormead, however, is academically strong too, and outperforms most other local independent schools anyway.
Both offer great extras and extracurricular.
Don't know much about new head of GHS, but I'm sure she's great - the school is the pride and joy, flagship school, of united learning, so regardless, they'll be keeping a close eye on it to make sure it does well - a good thing in this current climate, I would suggest! Tormead head been there maybe 5 years now and has transformed the place, it's well and truely on the map in the region and seems to move forward every year. Solid numbers, aparently full for this year despite the challenges of VAT are a good indication that its reputation is strong.
Girls nice at both schools.
Both great transport links and close ties to boys schools for extracurricular, expecially in sixth form. Tormead has recent acquired a great little prep school with a nursery, not surenif that's of any use to you.
I would suggest go visit both and see how you feel about them. Ultimately you do have to get in, yes, but it's also about what your DD likes when she visits.
Good luck.