I'd fit genuine BMW pads whilst your bike's still under warranty. I'm sure BMW would've bailed on my (continuing) warranty claim for warping discs if I'd used anyone else's. So I'd go to my local dealer, or the usual suspects (Motorworks, Motobins, Sherlocks) to see if they have a sale on...
I believe sintered pads will also wear your discs much quicker than non-sintered, although I recognise that disc life may not be your primary consideration.