any part of the city will be actually very suitable to live
I would have to disagree, the bus service is truly terrible, sometimes they come, sometimes they don't. Sometimes they are brand new air-conditioned buses, sometimes they are relics from the 1970s. The trams aren't much better, but at least they are more dependable, so when researching where to live it would be best to live on a tram line. Or if you move to 1000-lecia or Dab, then you can cycle to work in 10-15mins.
Avoid places called Zaleze, Szopience, Zawodzie, they are scumholes and more than likely you'll be targeted because you are not white, many, many football hooligans and undesirables live in those areas. Stay away.