GIMP, but you definitely should install also the GMIC and resynthesiser plugins. With GMIC especially, you're getting so many things that not even Photoshop can do, making GIMP objectively superior.
Edit: If you mean you're looking for a raw editor, meaning you change the colors and how the image themselves look, then you need Darktable. This is a raw editor. GIMP is mainly for VFX.