Today I´ve got a comparison for you. Zoya Kotori and OPI Midnight Blue Glitter looked quite similar in their bottles. Same dark grey base with blue glitter, although the glitter in Kotori is much a brighter blue. When I applied them, it was quite obvious they are not so close at all. The first layer was kind of the same, but after that, the differences showed up with each coat. Midnight Blue Glitter has much less glitter and a silver shimmer, while Kotori is packed with glitter.
They are both quite sheer. Next time I would probably layer them, but not over black, since I think the dark grey base is pretty awesome, so would use a grey as a base.
In the pictures I used 4(!!) coats of Midnight Blue Glitter and 3 coats of Kotori.
Index and middle are Midnight Blue Glitter. Ring and pinkie are Kotori.
I like the OPI better, it´s just gorgeous! Much better than I thought when I put it on my wheel. I wish it would be easier to photograph this, but unfortunately it didn´t show up as great as it is.