When it comes to pizza you are very well served in Berlin. However there are only a view places with goood pizza, good service and a good location. Most of the time at least one of them sucks.
If you are around Prenzlauer Berg you should consider checking out A Magica
Greifenhagener Str. 54, 10437 Berlin
It`s small, it`s cute, it`s warm inside and it has nice staff!