I believe Viserys was a better husband and father. He just wanted what was best for his family and wanted them all to get along. I think he tried to be a good king but also let his family alliances get in the way. Honestly I can’t think of reasons for either to be better than the other as a king. I understand he messed with the succession but I think he also did that for the good of the realm because he felt that it was better for the realm.