Both are amazing bags and the color is really beautiful, so you can't go wrong (though, like hightea, I also have a slight preference for the bleu minuit, which is just a shade deeper). To me, the diorever embodies the classic Dior ladylike vibe while the diorama reflects the modern / downtown girl vibe that Raf brought to Dior (and that Maria is definitely expanding upon). My personal preference is the diorama, but it's really about your needs and how you will wear it. One thing to note is that the diorever is much heavier than the diorama, in case that makes a difference to you. Let us know what you decide!