I did visit Barcelona about 2 years ago with my parents. I can see how it is a cool city but I didn't get to experience the nightlife so I can't really judge properly. We mostly did the weird touristy stuff :P On the other hand, the first time I went to Berlin was with my parents too but I knew right away that I HAD to come back alone because I just knew how amazing it would be. Did you eat Mustafa's kebabs in Berlin? Best kebab of my life.
I didn't eat that kebab, but as I have been living here for a while, I am very picky about my kebab (my fav. is in Ulm) What I did enjoy though were the Falafel in Neu-Kölln. You have to know, good Falafel outside of Israel/Middle East are hard to find. In Berlin its as good as in Tel Aviv and even cheaper! I liked how open (or rather "non-strict") the city handles the use and selling of marijuana. Big plus!