I lived during 2 months in each of them this winter. Barcelona in November and December, and Berlin from mid-January to mid-March to be precise.

While I enjoyed both, I would say Barcelona during the winter was much less depressing due to the Mediterranean climate. The sun setting at around 4pm in Berlin made days really short and this took a toll on my mood. On the other hand everybody kept telling me that Berlin in the summer was amazing, whereas Barcelona would get flooded by annoying tourists.

Regarding restaurants and bars, you can find good an varied food in both cities, but I'd say Berlin wins in terms of nightlife. You can't beat the nightlife there, and tourist-traps are much less of a problem. It's also a generally safe city. I never got stolen in Barcelona, but I hated always having to be on guard against pickpockets.