Argentina, definitely. It has the most beautiful landscapes I've ever seen and all kinds of climate. If you like it warm you can go to the north, mountains in the west, jungle in the east. If you like it cold, go to the south, high peaks and snow in the west, the sea, penguins and whales in the east. If you don't like extreme weather, stay in the plains, visit Patagonia, Merlo in San Luis Province, the Moon Valley in San Juan Province (it really looks like being on the Moon!) If you like the beach, in their summer (December to March) enjoy their beaches on the Atlantic coast.
If you don't want to travel around much, just stay in Buenos Aires. It's like a European capital, full of glamour and plenty of cultural activities. As for the budget, you'll find it amazingly cheap, considering that the exchange rate is so favourable for us now ($1 = 3 pesos) and each dollar goes a long way. You don't even need to buy a house or flat. You can rent one out for 350 to 500 pesos a month, if you consider you'll be getting a pension of some 6000 pesos, wow! you'll be quite rich over there. And their food is delicious, especially if you like beef! You can eat out for 6 to 20 pesos, according to the restaurant. A bottle of the best wine is 15 pesos. As for health insurance, the best is Medicus and it will cost you some 500 pesos for family coverage. In Buenos Aires, don't forget to visit the Colon Theatre and to go to San Telmo for a tango evening! You'll love Argentina as much as I do, I promise. I hope I can retire there myself!