Hey new member here. I am considering ordering a new G80, and have always loved blues especially on an M car. A local dealership happens to have recent examples of Portimao, Tanzanite, and San Marino, so I thought I would go check them out.
Unfortunately the weather today is cloudy and rainy, so keep that in mind. Probably none of the cars were "at their best".
I think it really is true that you have to see these colors in person to really decide your preferences. I expected to like San Marino the best, but in person I preferred Tanzanite by a pretty big margin actually. In the pictures I took though, I think Tanzanite doesn't look as good - too dark. I think Portimao looks the best in photos.
Also, they had some other M3/4s there, and I have to say Brooklyn Grey looks really good in person, especially with the extended shadowline.
Anyway, here is Portimao, which I think looks the best in photos. (The sky wasn't quite as dark either, which probably helps.)