One-room apartment or a room in a shared flat for one semester

I am a Master's student, and I´ll be studying at Göttingen for at least one semester. I am looking for
1. a one-room apartment (>= 20 m sq) for approximately 400 euros/month
or
2. a room (>=15 m sq) in a shared apartment, with about 3 or 4 people for about 350 - 400 euros.
I prefer a furnished apartment with no smoking in shared spaces.
A bonus would be a place with natural light and a dishwasher close to the north campus, but this is not a requirement.

I am a mature student, and I keep things tidy. I enjoy socializing over shared dinners, board games, long walks, or movie nights; however, I am not into loud parties. I have just started learning German and hope to get better at the language.