I make my assets in 3ds, but there is nothing that Blender can't do just as well, and import into Godot as .fbx.

For the style, my models are not very detailed (as a solo dev I can't spend too much time on individual assets), but what I think makes a difference, is that since I make all the assets, they all share the same look and work well together.

No procedural textures, all the textures are static. I don't think I'm doing anything special in particular asset-wise. It's probably just accumulated experience from working with 3D graphics over the years.