Hospital Italiano prepaid plan, 34 years old, 60 USD per month more or less. Insignificant co-pays (2 USD) in some cases, partial dental for free (cavities, one crown a year, cleaning etc), basic glasses, doctor can come to your place in a maximum of 2 hours or somethinglike that, waiting in the Hospital Italiano in San Justo (outside Buenos Aires) was something like 15-30 minutes once they saw I had the prepaid plan.
OSDE is more comprehensive and covers more centers, including Hospital Italiano. HI is good if you´re based in BA,or the north or west suburbs and you don´t need the flashy clinics (Otamendi etc), because the two HI big hospitals are maybe the best in Buenos Aires. If you can afford OSDE go with it, but for less money you can have also top care taking the HI prepaid option. HI also covers travels to the interior of the country and countries around Argentina. Maybe OSDE covers more countries.