I've lived everywhere in Paris. I'm not being sardonic when I say that. I really have. I've lived in the 2, 4, 5, 6, 7, 8, 9, 11,15, 18, and the 19th. It's not that I enjoy living like a nomad, I am just really shit at finding a long term apartment. I figured after having lived in so many I have a bit of knowledge now about what each neighborhood has to offer.
I didn't live in the 2nd for long. I lived at Strasbourg Saint Denis for a short time in the summer. It sucked. My window overlooked Boulevard Saint Denis, and it being Paris in the summer, and therefore hot as hell, having your window look out on that ensures that you will never sleep. This area is probably best if you really like partying because Grands Bouelvard is chavy, and the perfect place for crap nightclubs and overpriced bars. Also if you need to pick up a hooker. It's central Paris so you're pretty much close to everything. There aren't really too many points of interest here but you can branch out to other areas quite easily.
The 4th used to be my favorite area in Paris. And why not? Everything is there. I lived on Ile Saint Louis and then at the corner of BHV. One good thing about this area is that a lot of stuff stays open really late. You can get a burger at 5am (near Chatelet) for instance, but the crowds might negate any positives. You will never escape them. And on the weekends it gets worse because a lot of the streets turn into pedestrian only streets so they all flock. Not to mention I don't think there is one hour of the day that Rivoli doesn't have traffic. But if you like that sort of thing and hipster shops specifically dedicated to just hand lotion, or perfume, this is your spot. Really I'm not even sure how most of them stay in business, because that many people cannot be going there, but it's "quaint".
Another drawback is if you are a straight female, in fact female in general. This is "the gay area" and French gay men are not like Anglo gay men. They are mean, and they are bitchy, and I have been in more than one place where I wasn't even acknowledged because I was a girl. Someone once basically summed it up best, "it's a gay ghetto". So basically if you are neither a hipster, a tourist, or have a penis, maybe it's not for you.
Which brings us to south Paris. I'm going to start off by saying South Paris sucks. I hate, hate, hate south Paris. I mean there is nothing even remotely interesting to me south of the river. Everything feels different down there. The metro is horrible to use, and why is every bloody supermarket a Franprix? But anyway, when I lived here I lived at Monge. Technically where Lacepede hits Mouffetard, and if you are not into cheap student bars, you don't really want to be around Moufettard. The energy here is a lot younger and that's because it's mostly college kids. I didn't even like being around college kids when I was in college so..
The 6th is where I currently live. It's not the greatest but it's not the worst I guess. The buildings are beautiful, you can chill in Luxembourg when it's sunny, and around Odeon you can find affordably priced bars. They're a bit more posh, but I guess some people like that. I don't really have much to say about it, just that I now use the bus a lot more because the metro requires so many changes so I guess that's also an upside?
Next comes the 7th. Ah the 7th, rich American paradise. The most expensive district in all of Paris and home to many, many Americans (because those are the only people who can afford to live there). I work there, and at one point lived on the cusp of the 15th and the 7th (at Rosa Bonheur). I did not like this area either, not just because overground metros remind me of living in the projects, but because there's nothing in this area. If I wanted shops I had to walk to Commerce, or take the bus to Montparnasse, or if I wasn't feeling super lazy go down to Rue Cler (which is actually a really cute street). I mean the area I was in didn't even have a Starbucks and where today doesn't have a Starbucks? Welcome to suburban hell.
But that said, a lot of people will tell you it's a really nice area. I'll even say where I work, around Grenelle on the La Tour Maubourg side, it's got a cute little village feel to it. Everyone is always out on the streets, you can find a lot of high end epicerie and speciality stores, and if you're into celebrity stalking you might get lucky and catch a glimpse of Natalie Portman or Karl Lagerfeld.
Back up the river brings us to my time in the 8th. I lived off Haussmann and Miromesnil. Not the best area but it holds a special place for me. My favorite things about living here were giant Monoprix at Saint Augustin, best Chinese food in the city, Eric Keyser on the next block, and most importantly walking distance to everything. Seriously I never even realized how close everything was until I moved away. The drawbacks are that it's really fucking dead on the weekends, during the day when all of the workers go to lunch you won't find one place that doesn't have a line, and most of the residents here are bankers but it's bougie, if you're into that sort of thing. French bougie though. Which is slightly different from American bougie (7th).
On to the 9th.. I never appreciated the 9th when I lived there. Probably because I didn't live in the good area of the 9th. I lived on the border of the 9th and 10th at Maubeuge and Faubourg Poissonnière. It was a really, really boring area. I remember going out with my ex one night and not finding a bar that stayed open past 11. I lived here when I moved back to Paris in October so I didn't really have a feel for anything and going out was still boring, obvious places, but the 9th is great. I'll get more into it when I talk about the 18th.
When I lived in the 11th I was staying with a friend who lived on Trousseau, so we'll say Ledru Rollin was the area. This is a really, really great area. It's hipster, but not overtly pretentious. Like this was the area where I finally got used to being in Paris, in the sense that I no longer had to go out in a full "look", I could just throw on some Under Armour leggings, and put my hair in a bun, and no one cared (very different from the 8th, where I had moved from).
You have a lot of restaurants, and bars, and Faubourg Saint Antoine has a really great stretch of shops. Ledru Rollin is tree lined and looks kind of New Yorkish. You're really close to Bastille and Gare de Lyon, which I regularly walked to. You also have the infamous Rue Lappe which is like North Paris' answer to Moufettard. Further north you can find Oberkampf and Republic. Definitely go to the 11th if you want something laid back but hip. I like to say that the hipsters here retire to Montmartre when they get old.
The 15th was not a place I had every dreamed of living in. I lived at Dupliex for about two weeks (I couldn't do longer). I had been living with my friend and it was starting to get unbearable and a place opened up here. Now when I lived in the 5th, I lived in a modern new building (iPads and iPods in the wall controlled everything) but I was surrounded by Haussmanian old so it never felt like I wasn't in Paris. In the 15th though? Ugh. New buildings, don't adhere to the 6 floor rule and the vibe is just all wrong. This was also the first time I had ever seen a funeral parlor in Paris. And that's because all of the residents here are over 50. My say something nice? Commerce is a good street but otherwise this area was supremely boring and far away from everything. Why do all of the metros in the south only go through the south? If you must live in the South at least find something near the 4 or the 12 so you can go back up, otherwise it's like being trapped in an endless loop in hell.
After leaving the 15th, I found a sublet at Abbesses. It was a converted magasin near the Amelie grocery store. Now we all know my feelings about Montmartre, so I was really, really unhappy to move here but after a while I began to really like it. Yes, it feels 'different', and yes there are shit ton of tourists, but I liked being near Pigalle, Blanche, and Clichy. It's seedy and grubby but it's got a feel to it.
If you are going to move to Montmarte I would say stick south of the Sacre Coeur, west of Barbes and east of Clichy. Once you get to the other side of Barbes, you move into little Africa. The prices are cheaper and the flats bigger, but some people might feel uncomfortable there. And Chateau Rouge apparently has a huge garbage problem right now.
I would say really consider your love of hills if you move around Abbesses. While I like rue Lepic, trudging down to boulevard Rouchart to buy groceries sucked. Not to mention the stairs getting out of Abbesses station (you have to use the elevator) and then to my flat made me hate life. I had a boyfriend who lived one street up near the funiculaire, and I don't know how he did it everyday. His flat was even farther away but to be fair I think he mostly Ubered home... If you're not on a Marketing Director budget like he was, and therefore can't afford Ubers home every night, it might not be the place for you.
The last place I also lived was the 19th. I was still looking for a flat, so I needed a sublet for a short time. A guy listed his place near Place des Fetes. Now a lot of people have told me that this is a horrible area to live in, but at the time I only knew that it was on line 11 and that was the biggest drawback for me, not the crime or whatever else it's said to have. I had no problems when I stayed here. It's not touristy at all so you really feel Paris and the streets are quite a bit smaller so it's another one of those village feels. I lived off boulevard Belleville and I found it to be charming. My building was a new tower block looking thing, which was an eyesore, but the flat was big for the price and everyone else in the building was young. I once even took the nightbus at 3am to Montparnasse (and it was like a 15 minute wait) and didn't have a problem. Not to mention the police station was right down the street. I lived here when the shootings occurred, and because it wasn't central and touristy, that probably made it safer.
As for the rest of the areas, I have spent time in the 14th, 17th and 20th, my advice would be not to move too far out, only because it sucks trying to get home late at night. If you move too far out it also begins to feel like the suburbs. Parts of the 17th are okay (like on the border of the 8th) but you really have to be careful about anything that is near a "Porte" (code for you're on the periph). And don't let anyone tell you the 16th is "the" place to be" because it's "posh". It's new money, and you don't want to be that far out anyway. You basically only have the 9 to get you to and from, and it's like 40 minutes just to get anywhere interesting. No one worth their salt (or who has money) actually lives in the 16th. That's not "Paris", and if you live there you might as well be dead.