The Leica lenses were better than the Nikon lenses that were better than the Canon lenses that were better than the Pentax lenses, on average (there are exceptions to this). It didn't really matter at normal print sizes for usual focal length, but for example a 21/3.4 Schneider Super-Angulon for Leica from 1963 was a vastly better ultrawide than what you could have for other 35mm systems.
If you try to print big (let's say A3+) you'll rapidly find the limits of the m43 system.
If you try to print big (let's say A3+) you'll rapidly find the limits of the m43 system.