Congratulations, they are both great schools with really good Ofsted reports so you're in a win win situation.
My daughter attended Dalmain some years ago now. The current head had just joined as deputy.
She enjoyed her time there very much, progressed well and still has close friends that she made there.
She's now 23, has a Masters degree and is training to be a teacher.
A friend's son attended WOY and is also doing well.
I guess your choice could be influenced by the faith aspect if you are a practising Catholic...