I totally agree with Aaron. Regarding the oem inksets of modern aqueous inkjet printers, they all have good gamut for photography. If you are specializing in match proofs for critical advertising work the most recent Epsons may have an edge in hitting certain hues, but for general photography it’s kind of a non-issue.
What I would be focused on is the precision of dot placement ( dither ) of the various offerings. Although the latest Epson models ( 9570 7570 ) are using 300 ppi as apposed to 360 ppi in the pipeline as in all previous Epson models, reports that I’ve seen are that there is no difference in clarity and smoothness of output.
I recently had prints made of two of my files by different high-end shops on the new Epson 9570, HP Z9+, and Canon 4000. To me the Epson had the edge in color output and clearly superior black and white. The second best image quality, to my eyes, not using a magnifier, was the Epson P2000, then the Canon IPf 4000.
Again, with my experience, the dither differences between the three brands becomes more obvious at smaller print sizes say from 16x20 and smaller. It also depends on the kind of work you are printing and quality of the file.
A will also point out that I don’t personally do a lot of ultra-saturated photography or graphic design work on a regular basis and rarely on rc media. Those that do may have a different answer. In my experience the quality of the icc profile is a much greater determinant of color clarity than a difference between the Canon and Epson practical gamut.
John
After all these years of printing and running labs
My conclusion is don't just compare the color gamut when you want to buy a new printer.
I had a HP Z3200 which has the smallest gamut compare to the rest of my printers, 8300 and 7900 back in the time.
But the Z3200 makes the most beautiful print.
Another BUT, my workhorse was the 8300, mostly because the ease of use and the speed of it.
I have 6 epsons sitting in my lab now, including the P20000. to be honest, if time can goes back, i would pay a bit more to buy a canon Pro6100 (Pro561)
back to your question, I think the epson has a slightly larger gamut compare to the canon
that's it.
aaron