most of these use a base Fractal called Menger Sponge, combined with different math functions (RotateC, RotateAbs, translate, etc, etc) and other various fractals.
the renderer doesnt use anti-aliasing for still images but does have AA for Animations, it features a pretty decent depth of field though. i tend to the dof cause improves the realism a good deal.
i can directly share some of the formulas later for some of the projects,
then you can copy and paste them into Mandelbulb 3D, render them out yourselves so i dont have to