EmBrAer has always been my favorite example and perhaps the pride of South America. Que Toupe' Argentines have in calling Brasiliens inferior in any way! But then Argentina was the first country in Latin America to have a subway system, develop Nuclear Energy and quiet objectively contributed substantially to Medical Science considering its relatively small population. Yes the three Medical-related Nobel Prizes are something of an indicator, though perhaps not as much as the number of patents or successful companies as Camberiu points out.
I believe the two sides are somewhat right (The European diaspora side, the Latin side (in Latin America what French and US Americans call Latin is called "Criollo", gee) and the Brazilian side is absolutely correct because Brazil is a true melting pot with a very defined National Identity.
(Buenos Aires) Argentina is as much part of Latin America as Rioplatense Spanish is Spanish: it absolutely is, without any doubt, and still it's without any doubt quiet different from any other kind of Spanish spoken in Latin America. And there is a reason for that: The De La Plata basin received during the 20c an overwhelming influx of European immigrants that (temporarily) over-ran the preceding Criollo (Latin) culture in an extent that no other Hispanic-American country did (except maybe Cuba).
It's important to understand that Brazil received more European immigrants net than Argentina/Uruguay, but only in the latter they (temporarily) constituted the unmistakably majority (this would be a more absolute assertion when/if considering only Uruguay and Buenos Aires, not all of Argentina - and this misreading is the cause of many of Argentina's social problems, but not Uruguay's). However even in Brazil European-reported ancestry constituted a majority during a brief period in the 50s I believe (and that's counting Nationally, if we were to count the southern states they would be to this day as "European" as Uruguay)
It's certainly not an insult to call someone Latin, but to call Latin or Hispanic a third or fourth generation Argentine of full European, non Spanish, ancestry "Latin" for virtue of having been born in Argentina and speaking Spanish as a mother tongue might be a little misleading. Kinda like calling an American of German French descent "Anglo" without the benefit of the United States relatively well shaped national identity. An opposite example would be to imagine what the reaction of a Filipino being called Latin for being Catholic and maybe speaking a Spanish dialect. The Fiipino would probably not be offended, but certainly a little puzzled.
Are Afrikaaner speaking South African culturally part of Sub-Saharan Africa, the Anglo world, or are they "Misplaced Europeans"?
Assimilation doesn't occur overnight or even in one generation and is further complicated when the country the immigrants are supposed to assimilate to has been utterly changed by that same immigration - into something nobody really could define (I am reminded of a quote by Borges about the accidental nature of being Argentine). This was allowed (and complicated the matter furtherly) by the very Latin, Hispanic, Criollo, land-owning classes which invited the European immigrants in the first place and actively favoured the transformation of Argentina from an underpopulated backwater appendix of the carcass of the Spanish Empire to a veritable "New Europe" demographic experiment, only akin to those taking place in the US and the British Crown Colonies - and Brazil (and here's the tricky part, in the rest of Latin America to a much lesser extent)
During the 20th century Argentina was definitely considered the European part of South America in a similar way that Cape Town was considered the Paris of Africa, and to this day South Africa is a queer highlight in Subsaharan Africa.
Ayn Rand (peace be upon her) I believe never visited Argentina but selected Argentina as the last country before the USA to fall to Communism, and one of her heroes was Argentine (the only non American along with a Norwegian who's not even extensively featured in her novel)
Truman Capote famously closed Breakfast at Tiffany's with a quote about the perceived refinement of Buenos Aires.
Stefan Zweig migrated to Montevideo and or Buenos Aires before settling in Brazil. It was the move from the De la Plata to Brazil, not from Europe to de la Plata that provoked the most impact in him (see Brasil, the Land of the Future)
Definitely the countries that now constitute Mercosur are the most European-influenced part of Latin America in contrast to the countries that are now allied with the US and whose populations are more clearly identified by Americans as "Latin".
This is an interesting map. Notice the position of Uruguay relative to Portugal.
http://en.wikipedia.org/wiki/World_Values_Survey#Inglehart.E2.80.93Welzel_cultural_map
Terms are unclear and confusing, and the cultural identity situation is further complicated by particular situations:
Western European Identity, either Catholic or reformed, (Romance, that is Latin, Germanic or even Slavic) corresponds with the mostly Celtic lands that inherited their languages traditions and systems from the Romans and were only invaded and modified by the Germanic tribes and to a much lesser extent the early Turks (think Hungary), that is, All of Central Europe, Italy, Britain, Scandinavia, the Belo part of Russia. In some sense all of what used to be called Western Christianity is Latin or as we use the Latin script.
Hispania used to be part of that world, but much like the Balkans or Russia, it was slightly changed (even enriched) by foreign occupation. Spain was formed as the solution of the Christian European re-conquest of the Moor Kingdoms.
The Spanish and Portuguese colonization of the Americas was a direct continuation of the re-conquest of Iberia.
The term blue blood is traced to the days of the Spanish re-conquest of Muslim Iberia: Noble Christian ladies would keep out of the sun until their veins would appear blue in their pale skins to be able to differentiate themselves from those that sun-exposed or not, where of obvious moorish/european-visigoth mixed descent or outright Moors. The racial measure was transformed into a caste system that translated almost "perfectly" to the Americas demographic situation.
In Argentina there are (in addition to immigrants from all over the World) people of exclusive European descent, people with mixed Spanish and European descent, European/Spanish and Criollo descent, and Criollos themselves (the founding fathers of Argentina and their dependants) who are of all degrees of Spanish (and Western European) and Native American mixes.
In Brasil this caste system has not been ignored and I believe they used well into the 20th century terms that were only frequent in 18th and 19th century Colonial America (from Louisiana to Chile) to refer to the different castes.
There is one genetic factor that is unique to Argentina/Uruguay/Chile: More basques per capita than anywhere else outside the Basque country in Northern Spain/France. Similar to how the US is the place where most "Scott-Irish" can be found outside Northern Ireland.
The common ground is that both peoples, (in addition to the heavily Celtic Spanish Galicians) have too Occidental origins for Europe. Going to the West in Europe is good and a symbol of continental identity (if there is such a thing) but, too far west constitutes un-cultured "native" European. Asterix in Bretagne is a good example of that. The economic situation of Ireland and Portugal is another.
Disliked in Europe, they sometimes thrive in the Americas, and sometimes fall into the hillbilly stereotype or Barbados redleg one.
Camberiu makes an intelligent observation: Paraguay is the country that most resembles Brazil, and that's because Paraguay is the Guarani (Tupi) homeland, and Brazil is the land where most Tupis (Guaranis) call their home. Paraguay is the land of Mate (traditional, qualitative), Brasil the land of Guarana (commercial, quantitative) . Just as Uruguay is the most homogenously European country in South America, Paraguay is the most homogenously Eastern South American Native American nation, but Brazil have, numerically, more representatives of both groups. It's interesting to note that while most Uruguayans are actually genetically un-adulterated Southern Europeans they still embraced drinking mate as a National Symbol in contrast with Argentina where it can be almost a societal divide.
Guarani/Tupis are different from Andean indigenous groups in that 1) they never had any empire or glory lost to the Iberian conquerors 2) they benefited from Jesuit missionaries rather than ex-con adventurers and intermarried with the Iberians a lot earlier and in purportedly less coercive ways than the situation in the mighty dramatic Andes.
So definitely Argentina is, or had been for about 100 years, much like South Africa, quiet a distinct experiment from the rest of Latin America while still being part of it
Perhaps there is no equivalent of Argentina in Africa, perhaps South Africa is a more proper equivalent of Brazil.
A good mental exercise to understand Argentina from an American POV would be to imagine a historically independent Texas or California. Or rather to imagine the continuation of the European-American migration westward into Mexican territory without declaring independence or war, but rather submitting to Mexican laws and Spanish language while still being descendants of Europeans.
Since being white constituted an objective material advantage in the 20c (much like not being one constitutes one when applying to an American university or even job in the 21st) and since Argentine by virtue of political and geographical isolation is 20 or 30 years back, many Argentines to this day consider the "whiteness" of Euro-Argentina as a badge of honor and value. Even double-faced Peronists are White Supremacists at heart (just look at their candidates and historical affiliations) and there lies Argentina's perdition and Peru's future Glory.
Chile has had better luck with its white supremacism, but maybe it's because whites are a minority in Chile.
Uruguay doesn't care about supremacy because they'r all basically basques/italians (many from the North) and obviously Spanish. If a true pure native Charrua was found it would probably make the news. Black Uruguayans (1% I believe) are highly valued because of their Carnaval enhancing abilities, but less valued when they mixed into brown-ness.
If race was not so obviously correlated with language all of this would be extremely silly.