Portrait photographers who have shot with the Canon EF 85mm f/1.2L II will probably tell you about how wonderful that lens is. Having this particular focal length with such a wide aperture produces very unique and beautiful results. The new RF mount lens looks to take the crown for the best portrait lens, however.
A recent video from Matt Granger compares the two flagship 85mm lenses from Canon. Both of these lenses come with quite hefty price tags. The EF mount is currently priced at $1,849, which is incredibly steep, especially when you consider the age of this lens. If that sounds bad enough, you may want to look away from the price of the RF mount 85mm f/1.2L lens, because that is currently priced at an astounding $2,699. The new RF mount lens is much larger than the older EF mount version; however, surprisingly, it doesn't actually weight much more. This is one of the things I noticed when I shot with the EF mount lens: it's small but very dense. The major issue with the older 85mm lens was that although it produced some of the best-looking bokeh, it wasn't the sharpest lens when shot wide open, not to mention the terrible chromatic aberrations. The RF mount lens seems like a huge improvement.
Check out the full video linked above to see how they compare to one another and don't forget to download the files directly from Granger's website.