Apartment search engine Nestpick says its respondents praised the city for its thriving nightlife as well as its open attitude towards the LGBT community.
Canada was the country that rated the highest as three cities - Montreal, Toronto and Vancouver - all appeared in the top 10.
Omer Kucukdere, managing director of Nestpick, said: "Millennials have grown up in a shrinking world, where the internet has opened doors their parents never could have dreamt of, and budget airlines made those avenues real possibilities. It's now possible to live and work anywhere in the world, and these opportunities are shaping how our planet will look to future generations. We must learn to adapt to the needs of younger people in order to have a thriving economy, and we believe that this ranking offers valuable insights into those cities looking for regeneration from a younger demographic."
Meanwhile, it was previously revealed that millennials want to be "curious" on their holidays and explore new and exciting things.
Jacob Marek, an ASTA member and founder of IntroverTravels, shared: "I find that millennials are curious travellers and seek experiences beyond traditional tours and activities. There has been a shift in recent years from seeing millennials as low-spending backpackers and spring breakers into more serious international travellers."
Whilst Zane Kerby, president and CEO of the American Society of Travel Agents, added: "We wanted to get a real, third-party, outside look at what consumers are thinking and feeling. I think Wayne Gretsky said it best: You have to chase where the puck is going to be, not where the puck is now. It matters who you go with, even more than where you're going. That kind of surprised me, but the study shows that one of the primary reasons for people to travel is to spend time with loved ones and to create memories, not the destination itself."