Nothing is an easy to use intuitive api with all the features and all the performance, it's (Dx11) the sweet spot of where I felt like it was easy to learn and easy to use without worrying about performance too much.

Sure if you are building the newer rendering pipelines DirectX 11 leaves a lot on the table but it brought a lot of nice things with it, Debug Runtime alone was worth moving to it, 99/100 times your app written in DirectX 11 even if not optimised properly will perform better than DirectX 9 in my experience.

This holds with OpenGL though the modern OpenGL 4.6 and stuff wasn't bad, but it's a lot of cruft still.

Either way there are no perfect APIs, a truly general purpose API that just gives you basics like Texture handling and io and data mapping would be enough today imho. Fully general purpose compute APIs are the solution with some additional tweaks to make graphics stuff convenient. IMHO

Though it's definitely much harder than plain and simple paint colors and textures on vertices & geometry uv approach of old.