I can't recommend Marie's place enough. It's very close to the metro that takes you into the city in no time (never more than 30min), yet it's a calm area that allows you to come home after a busy day exploring Paris to recharge and enjoy life in the city. There are a lot of Bars, Supermarkets, Bakeries and anything else you might need within 10 min walking distance, so you can easily find everything you could need close by.
The place itself is beautiful, very clean and cosy. It's especially amazing if you want to rather cook yourself than eat out, which I can only recommend in Paris.
Last but not least, Marie is a wonderful host, always reachable for any questions you might have, always happy to help out with advice for your trips, or just a nice chat, and she really went out of her way to make our stay as comfortable as possible.
It's impossible to not feel welcomed by Paris when you stay with her and it was the perfect home for us to get a real feeling of the city while exploring Paris.
If you are looking for an affordable, cozy, clean apartment that's close to the city with a friendly, warm-hearted host, this is your best choice.