I think it would really depend on why you are in Argentina in the first place. I dont see any of those as a suitable substitute for Buenos Aires. None of the things I like about argentina are in any of those places.
I guess I would consider DF, in Mexico, as a somewhat interesting alternative- but for me the altitude is a bit of an issue.
But to compare Lima or Quito or Medellin to BA?
not for me.
Maybe Lisbon, or Paris, Barcelona, but all have their own issues.
A fair amount of my US friends have been buying in Portugal lately- its still reasonably cheap, but interesting and not collapsing under right wing austerity, like London or Rome.
But what possible similarities are there to a life in Buenos Aires to Asuncion? BA has 650 small theaters. 4 or 5 different music choices a night. 10,000 restaurants. Manufacturers of all kinds of materials and tools and products. A lively music, fashion, art, architecture, dance, literature, and film scene. A highly educated creative class. Paraguay has Mennonites and old fascists... and, I am sure, some very nice people.
San Miguel is full of geriatric artsy american retirees, illegal immigrants all, living a life of not much. Its BORING.
Is it really only about cheap? is that why you are all here?