Maoz Vegetarian is always a heaven for vegetarians and vegans. The principle is simple: pita bread, falafels, hummus, grilled eggplants and a lots of sauces and vegetables to add and you have a really good meal for less than 6 euros. I've always taken the Maoz Royal and I always loved it. This specific location of Maoz also offers a vegan couscous (which is good and generous) and a tasty Moroccan soup. Only some toppings are not vegan. Ask to be sure. The only negative thing of these Maoz is their fries: I find them really awful.
The place is well located at the very center of Paris and is open until very late, which is so convenient. There is a small sitting area but the best is to take away and go along the Seine which is very close. Staff is friendly and efficient.
Cons: fries not good, not 100% vegan