It depends on your needs. French drains simply drain the water without activating anything. Sump pumps, however, are active once enough water raises the float. Sump pumps can drain water so long as it doesn’t reach a level high enough to flood the entire basement.  Sump pumps are good solutions for unfinished/dirt basements and crawl spaces where some ground water is OK but you still want to keep your furnace, boiler, and/or water heater dry. Sump pumps won't necessarily keep your basement dry, but they will prevent flooding and can help protect your home's most critical appliances. A French drain will assist in keeping water from ever entering your basement to begin with and they can also be used in conjunction with sump pumps as a backup to keep the basement dry in extremely wet areas.