I agree with looking for 'Cafe de especialidad.' Someone already mentioned LAB, Surry Hills and Borja. I'd add Cuervo, Olí, Meme, Rita, Crecia, Lattente, Negro and RVR Cafes to the list. I've had flat whites at all, and they were delicious. If there was water added, I surely didn't taste it and the drink wasn't watered down. I'm not a fan of the taste of Starbucks or Juan Valdez coffee in general, so can't compare, but all cafe's I listed above use local roasters (Fuego, Puerto Blest) and seem to take great pride in their jobs. For food, where have you dined? Buenos Aires has an amazing dining scene (though it may be the cost prohibitive to get to some of the better options these days, admittedly). Hope you stumble on something that suits you, it's a HUGE city, there is bound to be a coffee and food joint you fall in love with. In my 11 years here, I've found many. Happy searching!