Is TextureFast better than Substance 3D Painter?

It depends on your goal. Substance 3D Painter excels at pixel-level control and procedural workflows. TextureFast is built for speed: describe the look in text and get PBR textures in seconds with no painting or node graphs. Use TextureFast for fast iteration, prototyping, and indie or environment work; use Substance 3D Painter when you need full manual or procedural control.