It all depends on what you need and like!! I personally prefer Asuncion over any other city in the country because of all the activities and nightlife available. Asuncion is full of modern shopping malls (La Galeria, Shopping del Sol, etc), movie theaters, theaters in general, cultural events, pubs with live rock bands (Kilkenys for example), high and medium end restaurants for all tastes (american (Hard Rock Cafe, TGI Fridays, etc), chinese, indian, italian, etc), concerts, etc. Asuncion also has modern high rise apartment and corporate buildings and the best schools in the country. However, its traffic is terrible during rush hours and the roads really need some fixing and painting.
If you prefer a more rural and slow paced atmosphere I would suggest living outside the major cities.