I recommend getting the 'whiskers' from MB original, although even they are slightly different than the orignal ones from the production days. The cheaper version of the repro parts offered by SLS and others are more or less worthless even if the price is tempting. The OEM-like version they offer is better/thicker but still not quite right.
While you're in there, I would also suggest to thoroughly check all the glued glass guides and plastic guides. Their failure is usually the cause for rattling windows.
Hans