Do you understand the consequences of asking that question?
OP unknowingly sparked a battle between two Reddit communities.
: when it comes to a city with an unending chain of clubs and bars, Düsseldorf is the place to go! We even have a song about it!
Cologne is way ahead of Düsseldorf when it comes to nightlife. You'll find more clubs, parties, and people out on any given night. Düsseldorf is better if you're looking for a super fancy night out, with top-notch bars and nightclubs. On the weekends, the Altstadt in Düsseldorf has lots of bars and small clubs, but it's mainly tourists and bachelor-party goers. The locals usually stay away.
I haven't been to Düsseldorf's nightlife, so I can't confirm this. However, I've heard that it's more difficult for Indians and people from the Middle East to get into downtown clubs in Düsseldorf. This could be wrong, so be sure to check before you go.
Cologne is bigger than Düsseldorf. To hear less mainstream music, go to Cologne. Bochum and the "Bermuda Dreieck" near the main station are great options too. They are close to the station and easy to get to.
of Germany
Cologne is a major techno music hub in Germany.
Didn't I think that was the same city?
I'm from Cologne, and I can tell you that comparing the two cities isn't fair. So, if you want to enjoy the nightlife, it's best to go to Düsseldorf. Cologne may not be the best option in terms of safety.