To weigh in on behalf of Paris... I think it's still a fantastic (and beautiful) city, I haven't been for a while but around (I think) 2012 my friend used to book me to dj there every month and I would go across and meet his friends, get fucked up for days on end and just have an amazing time. He is this insane character, almost a street urchin originally. who robbed to get by as a kid and was living in a kinda grotty cupboard in La Marais which was smaller than my bathroom in London, but it was in the right place. This guy always lands on his feet and keeps climbing the slippery ladders (I guess I mentioned before, part time catwalk model). Somehow he earned the patronage of Agnes B and I remember going to her office, helping ourselves to the champagne and steak they kept in the fridge for a normal working day, we just went partying all the time... lots of drugs and stuff, but also this guy is such a student of Parisien history he would always know the one restaurant that was left over from the old days and which was cheap and traditional and cool. We never went to clubs but we had fun for four days straight every time I went. Oh yeah he had a street stall and we would go to the Banlieu's on this weird bike he had with a trailer and buy stuff from second hand shops and then he would sell shoes he bought for one euro for 100 euros in La Marais, we sat there all day by the "shop" drinking coffee and playing chess against all comers while he ripped off hipsters. Messy times... sadly/luckily he's moved to LA now and is trying to write screenplays.
I definitely felt like you could still go and have a Miller experience there. It's massive, it's beautiful, it's all mixed, it has all these nooks and crannies and so on, it's like London basically. Maybe it's changed in the last few years.... but so has London.