Being from the US my wife and I are always trying to find a great burger in Europe with not a lot of luck. Then we found Menz Burger and felt like we were at a local burger place back home. The staff was EXTREMELY friendly and offered us a trial menu in English - even though we were more than happy to use Google to translate from German to English (we were in DE so our issue).
Our burgers were both AMAZING and accompanied by parm/truffle fries (which were also outstanding). If you are ever anywhere near this place it is definitely worth the time and effort to get there. It was cold when we were there in Dec, but they have a large open area out front that would be great in the summer time. This place is also off the tourist path so it is a great place to go and relax with beer and amazing food.
Honestly can't wait to get back to Cologne just to eat here again!!!