Midjourney is the strongest fit for producing custom diagrams and illustrations with consistent styling across a content library. Its style reference feature lets you lock in a visual identity by feeding it reference images, and its --sref and --cref parameters give you repeatable results across generations. For editorial illustration work it produces the most polished and coherent output of any image tool in this catalog. Ideogram is worth considering if your diagrams require accurate text labels embedded in the visuals, and Stable Diffusion is the better pick if you need full control through self-hosting and fine-tuned models to enforce a house style at scale without per-image costs.