Best Dog Breeds for Apartment Living in Major Cities

I am finally in a position where I can get a dog, but I live in a one-bedroom apartment in London and I am worried about the space. I want a dog that is happy living in a smaller area and does not need a massive garden to run around in all day.

I have been looking at French Bulldogs and Cavalier King Charles Spaniels because they seem to be pretty low energy. But I have also heard that some larger breeds like Greyhounds are actually total couch potatoes and can do well in apartments.

Does anyone here have a dog in a city apartment? How do you handle the exercise needs and the frequent trips outside for bathroom breaks? I am on the third floor with no elevator, so that is another factor I have to consider.

I want a companion that is friendly and not too vocal, as I do not want to annoy my neighbors with constant barking. Any advice on breeds or general apartment dog ownership would be great.