I hate to give you a weasel-worded answer, but... it depends. It depends on your budget and how you drive your car. I don't track my cars -- in fact, I don't even drive them all that hard anymore -- so I tend to buy inexpensive pads and rotors. Remember that ANY new rotors and pads will be far superior to grooved or cracked rotors and worn-out pads. I'd look on Roundel advertisers like Bavauto, BMAParts, Pelican, etc, and choose from their offerings.
Sage advise ^ I'd suggest not buying the cheapest rotors you can find, and yes, Roundel advertisers should steer you in a good direction on any purchase decision there. Assuming you drive like a responsible, reasonably-abiding, adult (as opposed to street-racing-rabid-tasmanian-devil-on-wheels), then pads that give you the occasional 1 or 2 no-fade emergency stops with otherwise good stopping-performance-when-cold might be a good choice. Again, see what Roundel peeps recommend. I tend to use Axxis/PBR ceramic pads for daily street driving. Stock BMW pads work well, but can tend to be dusty.
I have a question about rotors. In another forum there was a discussion about rotors and there were comments that the slotted and crossdrilled rotors were nosier then the standard. Has anyone noticed that? It was a Honda Odyssey forum and I was curious if that was specific to the vehicle or a common issue?
Yes, they are noisier and the feel through the pedal is rougher. Brake pads sliding over a surface with holes cut into it are going to pick up more vibration and noise than brake pads sliding over a smooth, even surface. You can chamfer the edges all you want, but you can't chamfer physics. That said, my personal experience is with a car with slotted rotors - I can imagine cross-drilled rotors might be a bit smoother, but cross-drilling weakens the rotor ever so slightly. Even slotted rotors still feel better than warped rotors, though! I'm taking a pass on making a snarky comment on the absurdity of "discussing slotted and cross-drilled rotors on a Honda Odysey forum" - anyone else want to take a swing?
I like these pads: http://www.tirerack.com/brakes/brak...W&autoModel=635Csi&autoYear=1986&autoModClar= Since I did not know the year of your 635, I arbitrarily looked them up for an '86 model. Not the cheapest in the world, but I dislike cleaning wheels (low brake dust!) and turning/replacing rotors due to semi-metallic pad damage. In my experience, they stop great with no more pedal effort and less fade than the stock pads. As far as rotors go: I buy good-quality solid rotors. Of course, since I mostly street-drive our cars (with an occasional road rally or autocross thrown in), I don't really need anything other than stock rotors. Drilled rotors are great for the track . . . but they crack from heat if you use them for the track! It would seem as if the are the very definition of a "Catch 22". Jeff