Favorite is desert, just for the light and the color palette 🥰.
Also it is easy for me to mistype and make into "dessert", which is quite funny, so extra points for "dessert biome" 😋.
Least favorite I think burnt forest or wasteland, because they are depressing, although wasteland is not as dark as in a21, I still do not like it. And personally I couldn't care less about higher loot stage or whatever.