Here is what people are wearing in Paris at the moment - whatever they want! I know people are always concerned about what to wear and at least in winter, you wear a heavy coat and a warm hat and scarf and whatever you like underneath. The brand I saw everyone wearing in the city is Canada Goose, you can tell by the shoulder patch, in fact there is one variation of the jacket that has some glowing buttons! I think there are now other companies that are adding a small patch to try and compete. It is so cold and so rainy that you really, really need a nice warm parka and don't worry that it's not city wear because it so is. Just be aware that CG is hella expensive.
In fact, here's an infomercial of alternatives to that very pricey line of outerwear:
https://spy.com/articles/gear/style/best-canada-goose-alternatives-winter-parkas-227439/