Mandelbulb 3D seems better imo, but i was used to Mandelbulbers tweaking tools, and i liked the renders i created with it, so i feel strange / nostalgic when using mandelbulb 3D.
-mandelbulb 3D has a useful realtime 3d navigation window which quite helpful
-you can combine multiple formulas in mandelbulb 3D
-animation seems easier
-seems a little faster at rendering too