Merton Oxford or St John's Cambridge

The college is a lot less important than the course (especially as a graduate student) so I’d make your decision on that basis. Both are great colleges.

Have conditional offers for both of them, which college would you choose? And why? (Studying part III I Cambridge Vs Mathematics and physics MSc in Oxford)

Part III Maths at Cambridge?

Have conditional offers for both of them, which college would you choose? And why? (Studying part III I Cambridge Vs Mathematics and physics MSc in Oxford)

Part III Maths Cambridge is a more renowned course and world famous, so can easily lead to a PhD.
MSc Physics is also great but is it what you want? Or do you want to do a PhD? 😧

Will the Cambridge part III really help for a PhD? If that's the case then you solved my issue (well, I still have to hope for funding🥹). I just don't really know how these things works apart from what is formally available online (or in forums). People in my country are a bit delusional when it comes to very high level education so it is a bit hard to get the right attitude. If you have any other non formal "knowledge" about part III and the other degree I will very much appreciate it.

Well, yes, I did read all the formal information. But it is hard to get the right idea as to what extent it will help to be accepted to a PhD if you are not inside this system

The Maths Tripos at Cambridge is world class and elite.
Oxford might be better if you want to do a Physics PhD. Cambridge if you want to do a Theoretical PhD. 🙂

Thank you 🙂

OP, thegeek888 tells us on other threads that he is an A level student who hopes to study law at a UK university at some point in the later part of this decade. He knows no more about the Maths Tripos at Cambridge, or indeed any course at any university, than anyone else who's read about such things on the internet knows. There's advice, and there's advice.
I agree with those above who have said that you should probably base your decision on the course, on future academic or career plans, and on any particular feel that you get when you visit Oxford and Cambridge. Each of Merton and St John's is a beautiful college at a great university.
The two cities are similar in some respects, but also quite different. Oxford has a ginormous car factory and, of the two cities, arguably has more city life unconnected with the university. That can be a plus or a minus, depending on your point of view. Cambridge has a slightly faster train to London, but Oxford has a 24/7 coach connection to London.
Have fun, whatever you decide.
SB (old person, knows zilch about maths, but knows about Oxford and Cambridge)

Thank you, I will think about it. The things is that you can take almost the same courses in part III if you want (but you also have option to take other courses).
I heard this thing about higher chances to get into phd also from other people but as you said, I really don't know how based it is. I probably prefer Oxford as a place but I feel that accademiclly (not just in terms of level, but in terms of various courses) I belong to Cambridge. So I am a bit torn between them. This is all still a bit theoretical discussion as I still don't know the funding situation for both of them.

Hi, I am in the exact same situation here, deciding between Cambridge Part III and Oxford MSc Mathematical and Theoretical Physics (plus I also hold an offer for Part III at St. John's!). I did not do my undergrad at either of the universities, but just by looking into the online notes and handbooks of both courses, I have the following summary which may be helpful:
Reputation and graduate prospects
The Part III is more famous due to its history, this of course has nothing to do with its teaching quality, course structure, etc., but it may come in handy when applying for PhD/jobs in the future. One thing to note is that passing Part III (and quite often, obtaining a Distinction) is a hard prerequisite for doing a PhD at DAMTP (in most areas, though it is definitely the case for the high energy and gravity groups), I believe some very selective groups (e.g. HEP and GR) even make Part III students take admission exams for their PhD in January, so if you want to do a PhD at Cambridge, or at least have that option open, Part III is the way to go.
Course structure and exams
The Oxford MSc has courses and assessments more spread out across their three terms. Specifically, there are assessments by exams and mini-projects towards the start of Hilary and throughout Trinity (Oxford names for Spring and Summer terms), some lectures are also entirely/partly assessed by coursework. On the other hand, Part III has most, if not all lectures in Michaelmas (Autumn) and Lent (Spring), then a big exam week in Easter, which is what your whole degree classification will be based on (with the exception of the essay, which may be offered as a substitution for one 3-hour exam). The Part III exams are also notorious for its difficulty, and personally I see the Oxford MSc as more forgiving/manageable.
Scope and breadth
The Cambridge Part III focuses more on mathematical physics, by this I mean even though they offer theoretical physics courses with the same name (e.g. QFT, GR), the notes seem to go into much more detail in terms of mathematical consistency and (sometimes) rigour. If you are studying specifically for theoretical physics, the Oxford MSc seems to offer a wider range of options, where without dwelling too much on mathematical intricacies, you'll be able to explore more topics, ranging anywhere from, say, geophysical fluid dynamics to superstring theory.
Of course, these are just my opinion based on things I found online, so take it with a grain of salt. Ultimately, your decision will also depend on more specific circumstances such as scholarships/funding, potential PhD supervisors and research areas, personal preference for the city of Oxford/Cambridge, etc. I am attaching some links below which you might find useful:

Btw feel free to send me a DM for further discussion as I too have not make up my mind yet

Cambridge has a much more theoretical and demanding workload with the courses but Oxford is just as demanding in terms of workload. However, Oxford might be much more of an attractive option, since you could do more Physics papers.
If you want to do your PhD in the USA or even here in the UK, then you would be better prepared by the MSc in Physics at Oxford rather than the theoretical Maths course at Cambridge.
If it was me, I would choose Merton College, Oxford. Enough said. 🙂
I wonder are you from China or Asia? Or Europe or USA? 😧

I gather from another thread that you claim to know this stuff because your cousin's friend did the Part III at Cambridge. I am not sure if you are being serious, or are trolling. Fortunately, there are some people on the thread who know what they are talking about. I can barely add three to five correctly, and I cannot tell quarks from bosons, but some here do not suffer from that impediment.