Drilled/grooved discs are all show in my opinion - and yes before you ask my discs are grooved and they look very nice thankyou very much
If you want to improve the stopping power and endurance of the brakes, you need to upgrade the brake pads to a material with a higher friction coefficient when at working temperature - often this material will have a lower friction coefficient when cold. Standard brakes will give you brake fade easily as the pads glaze over when they get too hot, but proper fast-road pads won't. Brake fade is when you are pressing the pedal, it feels really firm, but the car is not stopping. Another thing to consider is brake fluid - mostly forgotten about but if you fit a good set of pads, and do some fast driving, you'll probably boil the fluid. You'll press the pedal to the floor, all it will do is compress the boiled brake fluid and not make any effort to stop you.
Also, good for 'brake feel', is replacing the rubber brake lines with braided stainless steel hoses. They don't expand under pressure, so it makes the pedal firmer and the brakes more bitey.
My personal recommendation for everyone still running the single piston floating calipers is Ferodo DS2500 pads and standard discs. Get drilled/grooved if you have more money to spend and want them to look visually appealing but they won't give you better braking unless you are such a maniac you manage to cook a set of race pads, then the extra cooling will help. But for standard road use, a set of fast road pads and normal discs is just on, the extra cooling from grooved discs might overcool the pads, causing them to be less effective on the first bite.