Silver grey, Tiag, imola carbon black would be my choice. I would choose estoril blue but I just don't like it on the E46 but they are very hard to find too.
My dad had a Tiag one with CSLs was my fav M car by far just did everything so well. Then he had the E92 but that was so heavy, in a straight line was epic more power than you would ever need in any gear but just felt like a barge and the E46 feels like a go kart.

BMW E46 M3, Alston, Hartside, Cumbria, CSL wheels by TomScottPhoto, on Flickr
With my old 320SI
My dad had a Tiag one with CSLs was my fav M car by far just did everything so well. Then he had the E92 but that was so heavy, in a straight line was epic more power than you would ever need in any gear but just felt like a barge and the E46 feels like a go kart.

BMW E46 M3, Alston, Hartside, Cumbria, CSL wheels by TomScottPhoto, on Flickr
With my old 320SI