My preference would be a small private school - with christian foundations if possible for purely personal reasons. Where I am living now, I see first hand the difference in children who go to the large state school vs the small private school. Sad to say if you have a child with learning issues in the state system, they are destined to fall through the cracks - classes of up to 30 there is no other alternative really. Prep has no class sized cap here either and with only one state school in the area, they ended up with 36 students last year - no additional staff are provided as staffing is set in the first term of the year. Of those 36 students there were 4 ESL (2 with no english at all) and more than 6 with learning difficulties.
The same can be said if your child is exceeding their expecatations as the state system can provide additional stimulating material for the gifted child either in it's current format. This is in my town only, not generalising other state schools in other areas as everyone is different.