Oh, man! Please allow me to jump right in on this one!
My high school sweetheart was an exchange student from Belo Horizonte, Brazil (2nd boyfriend ever). He pretty much ruined me for any American/Yanqui men in the future! I've always been fascinated by people from other countries/cultural backgrounds in general, even before I had any romantic relationships. He seriously only resulted in exacerbating the problem. I have to be honest- for a good number of years, it's like I practiced "reverse discrimination" with the guys I dated. If you weren't dark (eyes, skin, hair) and didn't speak with an accent in English... well, we could always be good friends. Needless to say, this bias also got me into plenty of trouble later on (but I'd rather not incriminate myself

)
The Brazilian guy was a "stereotype," but in a very positive way- Charming, fascinating, had a certain "je ne sais quoi" about him, and had a personal warmth about him that Yanqui guys always seemed to lack in my eyes. Was I biased? You'd better believe it! And looks/physical attraction? HA! A smitten teen girl who was utterly gaga about her painfully gorgeous Brazilian BF can never have terribly positive outcomes!
I'll be honest- one of the things that I truly love about Brazil is that if you say, "I'm Brazilian," I can't imagine what you look like- You could be any color, any shape, any size, have any distinguishing features, but there is no "typical Brazilian" in that sense. Once again (forgive my bias, I know that there are always exceptions), but despite this wide range of phsyical characteristics, there is "something" about them that make them a personal weakness for me (or vice, depending on the semantics you want to use!).
Despite this, I'm married to an Argentine. Sweet, but very shy. Cute as can be, definitely attracted to him, but not "OMIGOD- Take me NOW!" hot. Same "je ne sais quoi" about him, but not a "charmer." But just like the Brazilian kind of "ruined me for other men," so did my husband. This is it for me. Not to sound cheesy, but if I was ever back on the dating scene again for whatever reason, I'd always be comparing anyone I met to my husband. It'd be very hard to take any future romantic relationship seriously.
In a nutshell- Stereotypes do exist for a reason, no doubt! But there are a TON of variables that can go either way. But here's the good news!: There are about 197,000,000 Brazilians. There are about 41,000,000 Argentines. Pretty equal numbers for both genders- There are quite a few to choose from!
Qué bárbaro!
Muito legal!