Not sure why you're asking, but internally university reputation depends on the field. Medicine (and probably dentistry) definitely at UNAN-Leon and second to that UNAN-Managua, UCA for a lot of social sciences and maybe law (?), UNI for technical professions. These are just my impressions from conversations, reviewing resumes for hiring, etc. I really don't know how you would know what university has the best reputation from the point of view of foreigners--I'm a foreigner, but I assume you mean those outside of nicaragua--but in terms of quality or prestige, probably the same ones, as they have various relationships, funding, partnerships etc with foreign institutions. Ave Maria College is the only one I know of accredited in the U.S., though I can't speak to its reputation besides being a place people learn English.