In this case it's not really a comparison between a DVC unit and a moderate as, although the Gran Destino is based at a moderate resort. the furnishings and amenities within the tower appear to be at a higher standard than other Disney moderate rooms/resorts. As a convention resort, Coronado Springs has more bar/lounge locations and food/restaurant locations than you will find at other moderate resorts or DVC resorts.
On the negative side, the tower itself does not have a dedicated pool -- the Coronado Springs main pool is a short walk via a bridge across the lake. In contrast, Riviera has a main pool, a leisure/quiet pool and a children's splash pad immediately adjacent to the rooms. Coronado Springs is also dependent on bus transport to the theme parks whilst Riviera will have access to gondola transport to Epcot and Hollywood Studios.
If I were making a choice between the two resorts, a major consideration would be if it was an adult only trip or if it was a family trip. I think kids would enjoy the proximity of the pools at Riviera, but adults would enjoy the more "grown-up" atmosphere at Gran Destino.