It depends on what you are studying as to whether or not a private school is a better option -- I think for instance Universidad de Belgrano is supposed to have a good accounting programme but some of their other degrees aren't that well recognised. Matias is right -- when I went to my husband's graduation from engineering at the Universidad Tecnologica Nacional there were some guys there who were well into their 30s -- they get jobs, work along the way, do the minimum per year. Honestly though, I think this prolongment of university degrees is contributing to the immaturity of a lot of people here in their 20s!
Yup, you're right. UB's degrees are well-recognized in these areas: Law & Social Sciences (International Affairs, Political Science, etc.), English / Languages, Business Administration, Marketing, etc. But you should NOT go there for Engineering or Computer Science.