I like Estoril Blue, but it is too common now. It's actually no more common than Black, white or Grey, but it's very distinctive. A friend had his F80 M3 in Hera Mica blue and that was lovely. A dark blue, not unlike Gentian Blue that Porsche do, but stunning in the sun.
I too liked Le Mans blue, and also Avus Blue on the E36s.
I don't understand why BMW sticks with Sapphire black - it's one of the most boring blacks around, always looks a bit dirty, and doesn't sparkle unless it's clean, polished, and a sunny day. Carbon black and Ruby Blac are much more interesting.
I like subtle colours, so will always like Silverstone, but I think the shade used on the E92 was perhaps darker and better?
I agree, Mineral white isn't the best white, and certainly much prefer the Carrara White metallic of my GT4.
I used to love Imola Red on an E46 M3. Probably the only flat paint I would consider.