The open model that closed much of the quality gap with the paid leaders, and the current favourite for photorealistic faces and scenes. Because the weights are open, it powers a growing number of other apps and can run on your own hardware or through cheap hosted APIs.
Using it well usually means going through a third-party interface or a tool built on top of it rather than one official app, which is a small hurdle. For realism and freedom from a single vendor, it is the one to know.
