which is better or are they the same?should i go with xdrilled and slotted or just slotted?

rotora slotted

rotora slotted and xdrilled


stoptech

 

Measure the thickness ratio of metal to air space on the vented rotor and compare to total weight [higher the weight the lower the temperature rise] of the rotor from sinking the heat created. The thicker the edge metal the better and yes even 0.1-0.2 mm matters on 9mm thickness, 7 mm ait then repeat of 9mm. Some rotors have thicker inside face than outer.

Internal rotor vent fin design is importantant as is the perfection of balance of the rotor.