Rarely in Paris do you find the combination of good, quick food, good service and free wifi. One striking exception is Noctudine, a small cafe that offers all of this seamlessly. I've eaten lunch there a few times and simply love the place. Below is my risotto with lardons. Other times I've tried one of the pre-made sandwiches, which they'll hot press for you until toasty warm. A variety of hot meals, salads and desserts are on offer.
Where they excel however, is service. They are extremely attentive, which is not surprising given that another part of their business is organizing receptions for large companies. The experience shows. Puffin comes here for lunch and then spends the rest of the afternoon surfing the wifi and sipping coffee (and probably eating desserts, though she doesn't admit this to me.)
(also at 73, rue Leon Frot, 11th Arondissement)