I'll be completing my applications for ds next month. I just had a look over the form and you can put down five options and by each choice there is a box for reasons for choice. I'm not sure what to write here.
Unless its a faith school that requires additional evidence of faith, or you have specific medical/social grounds for requiring a specific school (and the school prioritises such applications and you have external proof).... Then it doesn't matter! For Normal state schools for normal applications, anything you write will be disregarded. Admissions are on the published criteria, nothing you write in the box has any bearing unless as explained above.
I left it blank. I think it makes most sense to fill it in if your first choice of school is far out of your catchment area, or your child has a special need. If you're just selecting a school that's not your catchment school because it's a good school, then filling that in as a reason won't make it any more likely that you'll get in, (for legal reasons.)