I am now based in Munich, so I have not personally stayed at any of them in years. I have put up a number of guests at HI City Center, HI Westpark and HIX City West. City Center is very old and has small rooms. Top floor has a decent view of the downtown area. HIX is minutes from an S-Bahn stop, and HI Westpark close to U6 subway line. So location-wise, all of them are fine, 10 minutes from Marienplatz/city hall on public transit. HI Westpark is often cheapest, and also has the best rooms of the three IMO. No idea about the Nius in Munich, but having stayed at other Nius in Germany, I consider them worse than your average HIX, and far below HI Westpark. It really is a shame that Munich doesn’t have better IHG options … that new Königshof (Luxury Collection) would have made a great IC.