You have a number of things wrong in your post;
1. For the likes of HYP, top academic grades are a standard. They NEED to differentiate between applicants then based on their EC's AND interviews - as LIKE I SAID BEFORE, they could fill their incoming classes 100x over with students with perfect academic grades and academic EC's etc. I find this leads to a much more diverse student body, as where else in the world would you be able to have dinner and be sat next to one of the best regarded young poets in the world, an olympic level rower who took part in the 2008 Beijing Olympics and say the creator of something like Facebook? No where frankly.
2. I have indeed had an Oxford interview for E&M this year and being couched certainly helped - I was told in advance for example, that I would be tested on some sort of Game Theory question and was given soem previous questions which had been asked in interviews on this topic (one of which then later came up in my Economics interview). I was also then told how to answer questions whereby you are given a management study case, which you have to read and then answer questions on in the interview - it certainly helped going through various examples beforehand, and knowing exactly what boxes to tick.
3. I doubt the validity of your "some of my seniors abandoned HYP/ Wharton Huntsman to study at Oxbridge" - either they're complete morons, or you're lying here. I can speak for HYP on a personal note; they all have tutorials systems, they may be under different name (Harvard for example calls them sectionals), but its a known part of the teaching. So its a pretty moronic reason to leave one university for another based on this principle wouldn't you say
4. As for which has better undergraduate reaching, I have deliberately avoided this as topic as no one has had an undergraduate degree from both universities to fairly compare, and nor are there any objective data to say which is better in terms of teaching. So its pretty stupid to say 'IMO', as its just that - YOUR opinion, the opinion of ONE person. I could say the same thing about HYP
5. I'm sorry, but HYP on an international scale are MUCH more renowned than Oxbridge on the whole - I am someone who has had a quite tumultuous childhood and have lived in over 6 countries since the age of 2, ranging from Singapore, India, Dubai, NZ and England. I can quite categorically say that HYP are more aspirational/epitomised for students than say Oxbridge in these countries, just as easily as you can say for your ONE country.
Conclusion;
Read posts and research basic facts before you post such inaccurate nonsense. HYP >>> Oxbridge, unless you find me any objective date which says so otherwise (as thus far everything agrees with the aforementioned statement).