Does number of top grades or percentage of top grades matter more?

I'm not worried, more just curious. I got 999998888776 in my GCSEs (12 total), but would I be better off if I hypothetically only did 8 but had 5 9s and 3 8s in them? Top unis like Oxford always go on about number of A*, but is that actually more important than proportion. Obviously nothing I can do about it and most people seem to think about what I've got is fine, but just out of interest would be cool to know

It's better to have the more, because taking less you could very easily achieve the top category in all. Oxford usually look for 10A*s (at least for medicine), so that's 10 8-9s on average.
They also view these relative to your school, the grades other people get, because you could go to a 10 grand a term A* factory, but the grades you get there would be viewed differently to if you got them at your normal state school.
You should probably be fine applying to Cambridge (I only really know about medicine/dentistry) as they care less about gcses. Again, I don't know as much about other courses.

It's better to have the more, because taking less you could very easily achieve the top category in all. Oxford usually look for 10A*s (at least for medicine), so that's 10 8-9s on average.
They also view these relative to your school, the grades other people get, because you could go to a 10 grand a term A* factory, but the grades you get there would be viewed differently to if you got them at your normal state school.
You should probably be fine applying to Cambridge (I only really know about medicine/dentistry) as they care less about gcses. Again, I don't know as much about other courses.

I went to a state school where most people got 5s or 6s in everything. Thankfully, I'm not applying to Medicine!

I'm not worried, more just curious. I got 999998888776 in my GCSEs (12 total), but would I be better off if I hypothetically only did 8 but had 5 9s and 3 8s in them? Top unis like Oxford always go on about number of A*, but is that actually more important than proportion. Obviously nothing I can do about it and most people seem to think about what I've got is fine, but just out of interest would be cool to know

It's worth saying that only Medicine acts in this extreme fashion re GCSEs. Some other subjects are quite GCSE-oriented (especially if they don't have an admissions test) but many subjects have little focus on GCSEs.

The book: "Oxbridge Entrance - The Real Rules" is very interesting.
You need half your GCSEs at A* to have a realistic chance of success at an Oxbridge application. So, your GCSEs are fine.
OXBRIDGE ENTRANCE: THE REAL RULES: Amazon.co.uk: Pallis, Elfi: 9780954594497: Books
I wonder which degree course you're considering applying for at Oxford this October? 🙂

My son received an offer for maths. His GCSEs were good but not great 9988777665
His predicted A levels were 4 A\*s. His MAT was 76.
My take on it is that A levels and the entry exam gets you the interview. Then the interview and the entry exam gets you the offer. Not convinced that GCSEs matter that much.

Yes, this is what it is like for most courses that have an entry exam (barring medicine and dentistry)
For a course without an entry test like the ucat, esat, mat etc. they are known to use gcses and your personal statement, as well as your a-levels.