This really stands out to me -- the number of random people you walk past who are knock outs (guy or women). It is like there was some massive selection pressure for beauty several generations ago and now the average level of physical attractiveness in Buenos Aires is two standard deviations higher than any other country.
I think there’s some truth to what you say. This has been my impression as well. Some of it probably has to do with the walking nature of the city. Getting overweight can make people unattractive. I think lots of people would be good looking if they weren’t overweight and worked out. Having had weight issues in the past I noticed this in myself after dieting. I noticed a similar phenomenon when I visited New York City for the first time. People there were also more attractive than Southern USA where I was coming from. Tehran, Iran as well, which I visited, the women there were more attractive and not overweight. However, I noticed here in the afternoons the parks are filled with very many people who are working out, often in groups. Seemed very weird actually just because of the high number of them. I didn’t notice this sort of thing when I visited New York City. I also noticed some areas of Buenos Aires, like in Recoleta, Palermo, and Belgrano, people seem more attractive than in Downtown and Puerto Madero. Some of that might have to do with the tourists that may be more there near the Obelisk and the River. Though obviously none of that is scientific, just my impression. But what makes you say Portenos are better looking than any other “country?” What about a place like Japan? Women there are very attractive it seems. Korea as well probably.