slotted is enough to out gas the brakes & keep the pad surface clean without being like a cheese grater, slots are more like "slicing/shaving" rather than "grating" & less aggressive wear overall for the rotor & pad... blanks are the least aggressive but fade easily when heated up, best for a commuter car that will be used conservatively, if you always drive conservatively then the blanks will last the longest, but for spirited driving at least I'd say get the slotted
+1
I run drilled and slotted, just because I think it "looks" cool. I've actually read that blanks are the best, because it creates the most surface area for friction.
Drilled = creates "invisible" hairline fractures regardless of how you drill it. This makes it more prone to stress fractures. Porsche actually CASTS their rotors with holes and are not drilled, this is the way to go but cost a lot and no known manufacturer even offers this as an option. Helps avoid warping too with more cooling due to the holes.
Drilled also gets brake dust stuck in the cooling vanes of the internal side of the rotor -- most will get cleared away but I guess it still adds the possibility of build up. Almost all companies recommend plain or slotted for "severe" or "track" driving.
Slotted = quicker initial bite because lets gasses escape -- if the slots are done right... and the slot goes all the way to the edge of the rotor. Slightly reduces pad life, but also keeps them clean by "deglazing" them at each pass, especially as the rotor wears out and the slots get sharper... They also create a sound when braking -- which I love because you can "hear" the car stopping. Some might find this an annoyance.
Drilled and slotted = pros and cons of having drilled and slotted, but even less surface area.
Official Porsche cars that come with cast holes are still replaced with blanks when they are on the track.
In a perfect world, I would only get slotted only, but cross drilled looks too good for me to pass up.