I just had the original front brakes replaced on my '98 E320 with 65K miles. Rear brakes still don't need replacement. I used OEM Mercedes pads. I'm very happy with the life of these pads.
Many people swear by only the Mercedes pads. Yes, they do give off a lot of dust on the front wheels, but Kleen Wheels works great for me.
I'm confident there are many threads on this topic in this forum, and there are also many on the Mercedes Benz Club of America forum. On MBCA, most agree that the OEM pads are best and others will give you problems in the future. I cannot confirm this, I'm just repeating what others have said.
Also, my independent auto mechanic who specializes in Mercedes' repairs also did not recommend going with non-OEM brakes. I'm happy with my OEM brake decision.
2000 Lexus RX300