Switched from Epson (9600, then 9800) ten years ago to Canon (8100, 8300, 8400, now Pro 4000.) I run a small commercial studio and print every day. Canons have been very reliable and head changes are as easy as ink cartridge changes. I replace the head about once a year on the 4000. As far as image quality goes, I don't see any significant difference, although I do prefer Canon blues, such as skies. Maybe this is because of the blue ink in their ink set? They did drop their green ink with this generation and put in a clear "chroma optimizer." I thought I would miss the green for landscapes but while there is a barely perceptible difference, I don't find it a problem. And while I was skeptical about the chroma optimizer, I've learned to love it on glossy papers.
One thing Canon has improved with each generation of inks is their resistance to scratching and buffing. Of course, large dark areas on matte papers are always tricky with any printer, but the Canon printers seem to do the best in this area. Also, although I haven't measured it, I do feel I get more mileage out of an ink cartridge with the Pro 4000 than any printer I've ever owned.
While I can't say I rave about paper loading, I don't find it a problem worth complaining about and I changes rolls a lot and mix in all sorts of odd sheet sizes, not to mention strange hand made Japanese papers, super thin stuff, fuzzy edges, etc. Rarely a problem.BUT like others have mentioned here, some papers with significant curl at the end of a roll can be problematic.
And of course, the bonus for using a Canon is virtually never a problem with streaking caused by head clogs!
Biggest negative? Not with the printer, but with the Print Studio Pro software. It's a big step up from printing through the Print dialog box, but a step down from the simplicity of the old Photoshop plug-in used on the 8xxx series. I'm used to it now, but it has some utterly stupid "features" that tripped me up initially.
Overall, really happy with Canon printers. I don't miss anything about Epsons!