OK this is all extremely personal and based 99% on rumour!
Matthew Arnold (where ds will go unless something very unforeseen happens) is not bad at all. It's the smallest of the Oxford state secondaries (which isn't saying much) and has good results at the mo (81% 5 A-Cs and all that IIRC) plus they can do separate sciences which I like. In general I hear reasonable things about it and I know some girls who are currently there who are pleasant. When I did an A-level there as a private candidate I thought it was strikingly dirty and neglected in places but liked the relationships of staff and children that I witnessed. Apparently it used to be amazing at history but a history teacher went off on long-term sick. The turnover of staff is relatively high but that's from 2 years ago.
Cherwell is the 'top' state secondary - don't know exact results but I was at Oxbridge with numerous products of their sixth form. They have no uniform (which I like, wish MA didn't either). It's rather enormous now but the early years are on a separate site from the later years. There are persistent rumours of drug problems but frankly I think that's a problem in the whole of Oxford not to mention the whole of the country.
Magdalen College School is one of the most successful boys' private secondaries in the country. My ILs live next to a boy in the early years there and I would say it's extremely hard work there - I probably wouldn't choose it for ds even if I could afford it. having said that, it has an absolutely amazing reputation in terms of atmosphere and all-round achievement. I know one of the people involved in pastoral care there and she is lovely.
The Oxford Academy/The Peers School is.... well, it's just relaunched, it presumably has a new head and lots of new money as an Academy, so it has potential. I have never been there. I probably would have home-educated rather than send ds to the Peers but a school that is on its way up has a lot going for it. Ds attends a primary school that used to be avoided by parents locally and it's lovely so these things are never simple.
don't know anything to speak of about the others.