The original topic was Argentine Sweets and then became a little of everything you can drink or eat, so here my contribution as a native:
Fernet: I don't like it very much. It seems to me just a cheap way to get drunk, and I guess that's why it became popular. I can drink a bottle of beer (5% alcohol) without visible side-effects, but I cannot say the same after a few glasses of Fernet (45% alcohol), even with Coke.
Medialunas: I like them, but I'm not a fanatic.
I really find it difficult to find good pastries/bakery in Bs. As.
I think that economic situation over the last ten years, have influence negatively in the quality of food in general. Many places had to resort to make smaller pieces and/or cut the quality of their products to survive.
When I was in San Diego (CA), I didn't miss medialunas at all, I had a delicious breakfast made of a fresh and warm slice of french bread, scrambled eggs, maple syrup and bacon, for about 10 dollars. I don't know where to have a breakfast like that here, but a blue-rate it will cost 150 $ pesos, which is a little too much for a standard local breakfast (Café con Leche y Medialunas).
Coffee: I personally like the one that is served at Café Martinez. For home, I bought ground coffe (no sugar added). Café Cabrales, Los 5 Hispanos, Martinez. etc.
The beverage -they call coffe- that is sold in vendor machines is just plain awful to me. We called that: "Jugo de Paragüas"
Mate: I drink it everyday, but only till afternoon. If I drink it at night I won't be able to sleep for hours.
Alfajores: Don't like them especially, too much sugar to me. I eat 3 or 4 "Havana de Nuez" a year. No more than that.
Pizza: I love Bs. As pizza in general, and perhaps (i'm embarrassed to say) especially the unhealthy kind, like the one at Las Cuartetas.
I would never say our pizza is the best, just that I like it. I eat pizza on fridays night at home. And perhaps two slices (al corte) at lunch every now and them.
Icecream: I could eat a kilo every day ... but i don't
Cousine:
Somebody said something about Peruviam cousine. I have to say, I do love it. I guest there are going to be better restaurants in Perú than here, but there are quite a few to give it a try (Sipan, Ceviche, La Rosa Nautica). I'm wishing to go to La Mar (from the same cheff that Astrid & Gastón, wonderful restaurant, but closed now.)
Sushi: I love Sushi. Many said that is expensive (I agreed, good quality sushi it is), and many say it is not that good also, well I can't debunk that, but I willing to hear recommendations of good sushi restaurants here or in your homeland.
Milanesas: Only like the ones my mom used to do. I'd never order milanesas at a restaurant.
Empanadas: I love the ones I cook myself, and I'm willing to share the recipe to anyone
Asado: I enjoy very much making an asado, perhaps much more than eating it. I usually spend +three hours in the process, listening music, drinking a good red wine. At the end, the grilling process is just an excuse to enjoy a sunday night (or day) in family. The cuts I like more are: Vacío (Flank Steak), Entraña (Skirt steak), Ojo de Bife (Ribeye), Bife de Chorizo (Sirloin Strip Steak), Tira de Asado (Short ribs), Costillas de Cerdo (Pork ribs), Matambrito de Cerdo (?).
I don'k eat any kind of offals/entrails (achuras), nor blood sausage (Morcilla).
Hope I didn't bore you with all this stuff.