Most usefull nodes i used are not math and not available in Blender nodes.
Many mix modes, many clamp, spawners, geomtry shapes, advanced gradients, edges dither, height map nodes, bump mixing nodes, many more different noise and patterns generators; and lot more nodes that are work on texture and not math advanced.
I seen some cool Blender materials, but it’s too much Blender nodes needed because lot of nodes are missing, so it’s lot more work and work around compared to Substance Designer, sand many things are not possible in Blender shader editor nodes.
In Substance Designer you can make great materials without going advanced complex nodes.
Just using noiss generators, mix and masks nodes, random spawners and color ramps.
While Blender only have very few of those nodes and some does not exist in Blender.
While it could improve a lot if there was people working on it.