Hmm. Very dependent on the child, I think.
We tried our local comp (which sounds v similar to yours) for our eldest. Great teaching, extra curriculars and he had a circle of really nice friends. However, it was ultimately a disaster for him for two reasons.
The first was the strictness of the school. DS has ADHD, and although really bright, was always falling foul of the multitude of regulations - non-matching socks, forgetting a pencil or part of his PE kit, you name it. He was constantly in detentions, despite being otherwise well behaved and high achieving. This was pretty soul destroying for him.
The second was a contingent of rough kids at the school who made DS's life hell (DS stood out as being clever and a bit quirky). Bullying escalated to serious physical assault on a number of occasions, with police involved. The school were amazing at dealing with it, but it left our previously happy go-lucky DS badly affected in mental health terms.
We moved him to a private school which was a much better fit for him, and where he is now happy and achieving. So 100% the right decision for him.
DS2 will be going to secondary soon, and we will choose private for him for different reasons. He has mild SEN, is not massively academic and will benefit much more from smaller classes and more attention. We're also worried about potential for him to go off the rails if he falls in with the wrong crowd.
I know plenty of friends' kids who do well at our local comp. And a friend's child who struggles and is miserable in the "bottom" sets at a super-selective grammar school (which otherwise looks amazing on paper). So I would think carefully about your son's character and needs and your gut feeling on whether the schools you're looking at are right for him (and whether there are any other options if not). Lucky to have the choice!