Best soaps on the planet are Marseille, and Alep soaps, along with some other less known but just as good soaps produced around the Mediterranean sea.
It can be hard to find real ones, for they are so renowned that many companies reuse those names to sell shit soap. When you get the real stuff, it's just 100% of one of the most concentrated soaps you can find, as anything more concentrated would hurt your skin. Actually, if your skin is too sensitive, Marseille soap WILL hurt it, but Alep soap is softer.
It's commonly used in Europe and Maghreb as an all purpose soap, which is just as well used to wash the floor, do the dishes, wash your body and hair, and even your teeth if your mouth can stand it. Most European commercial cleaning products, detergents, shower gels and shampoos are for the most part dissolved Marseille soap.
They are, in fact, similar to Castille soap, except originally produced in different areas with different recipes which gave them different names, Castille soap being the softest, and Marseille soap being the most efficient. And you'll surely think "hey, Dr Bronner soap is Castille soap!", and this is where it gets dirty.
Aside from Europe and Africa where those things are closely regulated, any soap made of at least 72% of olive oil, regardless of the quality of said oil, can be called "Castille soap" in America, even if they contain sodium talowate or sodium palmate / palm kernelate, so either you wash yourself with bacon or frying oil. Just check this and you'll learn what their soaps are made of:
https://www.drbronner.com/ingredients/fair-trade-around-the-world/Actual Castille soap is supposed to be made of 100% olive oil, which Dr Bronner soap certainly isn't, and even then, Alep soap contains 75%, and Marseille soap 72%. So you can't know what you're buying in America, you could piss in cheap olive oil and call it "Castille soap".
So yeah, you can get much better than Dr Bronner soap, but you'll have to order it from Europe or Africa.
