Can anyone advise re Oxford colleges for Maths?

[GeorgeTheThird]

DS1 will be applying this October and has a reasonably realistic prospect of getting on an excellent maths degree course. (All A /A^ at GCSE and A in his mocks this year). He loves maths, does extra maths, reads about maths, does the Olympiads, is happy to do MAT and STEP papers in his own time... etc

Can anyone give any help as to which college to apply to? He is at a mixed school in the North that is only moderately selective, enjoys music and debating but is not at all sporty. He is sensitive, articulate and not at all arrogant or "macho" (for want of better descriptions), he is not massively competitive and is open to applying to a historical college but not especially set on doing so.

He has been wondering about St Anne's and Keble? Any ideas, anyone?

I was at Keble in the early 80's. As was OH, who read maths.

Is this the link, although it does advise treating the results with 'extreme caution'?
www.ox.ac.uk/about/facts-and-figures/admissions-statistics/undergraduate/additional-info/college-success-rates?wssl=1

I second (or third, or whatever number you're up to) the advice about picking a college by gut instinct as much as anything. Unless there's one super duper academic you really want to study with - in my day, being at their college did make a difference to access. But I chose my college based on its resemblance to Hampton Court, and it was as good a method as any. I made lifelong friends there and enjoyed both the study and the life.