Unless you are into racing or at least a semi-professional race car driver who takes your car to the track, most of us don't need brakes that exceed OE (Original Equipped) specifications.
Slotted Rotors: These are rotors with slots(grooves) usually about 2-3mm deep. This design is more aggressive on the brake pads, although it acts like a razor blade shaving the pads every time you hit the brakes; they make sure that the pads are clean and have good contact with the rotors. Recommended for racing applications.
Cross Drilled Rotors: Holes are drilled halfway through the cooling vanes on each side of the disc for vented rotors. While the rotor is spinning, the vent create a turbulence that draws extra cool air through these holes. This method cools the rotors faster and decrease the chance of warping the rotor. A warped rotor causes vibration when you tap the brake pedal.
OE (Original Equipped): OE specification rotors are manufactured 100% according to the manufacturer of the vehicles. In terms of thickness, vane design and fitment, they must be identical. For most drivers, this is the most cost effective way to replace your OEM (original Equipped Manufactured) rotors.
At the end of the day, it really come down to your application, budget and durability. Knowing your own driving habit can help you decide which product is suitable for you. If you tend to brake heavy, you may want to avoid the slotted rotors.