Which neighborhoods best to stay in? (Berlin)

Hey everyone,
It looks like I'm going to move to Berlin in the near future (I'm German, coming back after 16 years).
I don't know Berlin well so I was wondering if you had any tips which neighborhoods are best/nicest/affordable to stay at?

I'm going to come over in November for a few weeks, so maybe I'll meet some of you at some Internations events!

Thank you,
Anja