There's one thing you learn over time, unless you're going to upgrade the calpiers to 4 or 6 pot and upgrade the brake fluid and add braided lines, there's not much point in upgrading anything else. By all means go for bigger diameter discs as there's more surface area but the best option is to choose a far superior pad. Drilled discs tend to lend themselves to cracking and grooved discs are rather noisy under heavy braking.
Heat dispersal is another big point. I'm using 308mm 16 groove discs with EBC Redstuff ceramic pads and I've turned my discs blue over and over again under heavy braking which in turn boils the fluid leading to complete brake fade.
I have had drilled discs, grooved discs and plain. As an opinion goes, I would opt for a larger plain vented disc and a high quality pad.