I had the choice between 2 comps with identical a-c results and value-add, so I chose mainly on their setting/streaming policy.
My son struggles withEnglish (though he scraped a level 4c in y6 SATs), and I did not want him streamed low sets for everything based on his dyslexia. If you scote liw at English, you go in bottom streams for all humanities.
The other school (the one we chose) does minimal setting, also there is lots of movement, they already moved DS twice, as based on CATs he was placed low, but worked well in class so he is now middle set. Most subjects are not set though (only maths, English, MFL and PE, yes PE, as the school want the not-competitive not-sporty kids to enjoy a more gentle PE session)
It depends on your child, IMO, with a "bright" academic child, streaming/setting can be great, they go to top sets and that is where they stay.
For lower to mid- attainers it is nice to know they are not "relegated" to bottom sets too early, especially for boys who often do not start working hard until gcse!
My second DS is very academic so I'd be happy to send him to the other school if he wants.