William Smart or St Nicholas

Hello-we are a non Cantonese family with our son 2.5 years old. He has been admitted to William Smart and St. Nicholas - both local stream.
He has been learning Cantonese since he was 9 months so he has some understanding. For us we think he will be fine and will learn fast but we don't know which school to choose.

Which would you choose and why

We are very confused.

Thank you.