Canon's interchangeable lenses have long been great performers, but, advantaged by new lens designs made available by the optimized RF mount, the RF lens lineup is nothing short of awesome.
Usually, RF lenses outperform all other lenses in their respective class.
During a conversation with Canon engineers at a press event introducing the first Canon R-series full-frame mirrorless interchangeable lens camera (MILC), all RF lenses were promised to have advantages over their EF lens counterparts. Potential advantages include smaller size, lighter weight, and new features. The Canon engineers also indicated that RF lens image quality would be minimally equivalent and often better than their counterparts. Reality is that we are seeing the "often better" advantage appear more like almost "always better" with many lenses delivering simply amazing image quality.
From the beginning, Canon's RF mount lenses set the image quality bar very high, and the other features of these lenses, including AF performance and image stabilization performance, are outstanding. Most of these lenses alone justify the purchase of a Canon R-series full-frame MILC.