In answer to the op, I can give you a very strong reason why a good school was much better for my son than poor school. He went to both and ended up at the 'good' school. A move that may well have changed the course of his entire school life and beyond.
When my ds1 was 7 (in year 3) he was at a large, state primary - didn't do well in ofsted league tables, lots of temporary teachers, big classes, but it was very local. That's why we moved him there.
My son was a handful - always had been. Lots of low level disruption - not listening, very poor concentration, distracting other children, wandering round the classroom etc. Teachers said he was bright but was performing far below his ablilty. He was at one point put in the remedial catch up class for reading and writing. He had been on the school's SEN register for his behaviour, from the end of year 1. In year 3, was just about to move onto the next level of seriousness - ie the SEN teacher thought his behaviour was getting worse. I was at the point of accepting that my son had special needs, needed diagnosis and was beyond the help of his teachers. My son was picking up this idea, too and I could see he believed that behaving 'normally' was beyond him.
The school was big, (3 classes per year group). The playground was full of little boy gangs - my son was involved in countless incidents of hitting and kicking. He was often in classes of 40 or more children with a variety of different teachers, as there was a staffing problem and classes were spilt into larger groups.
My son was on the waiting list for a small, local church school - still followoing the same national curriculum. The school had been rated by Ofsted as 'outstanding' ie amongst the top 5% of primary schools in the country. A place suddenly came up for him in year 3.
When he moved his new teachers assessed him. Within a few weeks they called me into the office to tell me that my son was definitely not special needs. They were not putting him on their SEN register. They told me he was quite capable of good behaviour but has been badly taught. He was put in all the middle to low sets.
It would be untrue to say his behaviour suddenly and magically improved. It was a long hard battle in year 3/4 but slowly things improved. By year 4 he was a total Harry Potter fan, avidly reading the books to himself. He was also moving up the ability sets. In year 6 he was in all the top sets and passed his 11+, one of 7 children in his form of 24 pupils.
I was in touch with parents from his old form at the other primary school. AFAIK, none of his class passed the 11+ - remember, these were children placed in higher ability sets than my son.
In our area, the choice of secondary schools is very difficult. If you pass the Bexley 11+ you can get to a grammar school (in the next borough) if not, the secondary schools are all way below the national avarage.
I do not know how my son my would have coped with a secondary school here - his primary headmaster strongly advised me not to put him in one of them. I know of other children, however, who are doing very well. My son likes his school as well. And as 100% of the children got grades A - C for GCSE, there's a good chance he will come out of school with good basic qualifications, at least. The chances of this happening at the local secondary school is much smaller.
When he was at his first primary school, I would never have thought he would have got to a grammar school and I totally believe he would not be there if he hadn't changed primary schools when he did.