>>3025402The most popular are the Gradio UIs: A1111/Forge/Reforge. Those are the easiest to use and can do 90% of what people need for imagegen, plus have extensions to do more.
The next most common is ComfyUI, which is a node based interface. This doesn't do anything by default so is harder to use out of the box because you have to build a workflow or find it somewhere. However, ComfyUI has custom nodes and gets support for newest technology the soonest like WAN video gens and such.