Most people who tell me they want to visit Argentina have a simple request: they want to see 'La Patagonia'. Though I have not traveled extensively in the region (which is about 1/3 of the whole country), I was more impressed by the North-West (NOA). And I was stunned more by the glacier Perito Moreno than by the Iguazú falls.
Of course, it all comes down to personal past experiences, expectations, company... and luck.
What are your recommendations to friends and family when visiting Argentina? What did you like the most?