My personal favorite was this little coffeeshop in the 3rd Arrondissement. Quite busy, especially on weekends - but it's worth the wait. And basically everything I tried was yummy, especially the granola and the avocado toast.
+ this place is very instagram friendly, just look at those floors and that marble table !
54 Rue de Saintogne, 75003 Paris
This coffeeshop is part of the very famous concept store, Merci. It's the perfect spot to sit down between a shopping stroll and the interior is really cute - you're basically surrounded by big bookshelves and on the other side you have big windows where you can style stalk all the people visiting Merci. And well, drool over that cute red car.
111 Boulevard Beaumarchais, 75003 Paris
The Broken Arm
Basically worth a visit already because of that yuuuummy cronut. Cute interior and also very photogenic floors. Also quite busy during the weekends, so I would recommend visiting it during the week.
12 Rue Perrée, 75003 Paris