I have a Canon Pixma 5000, which is a couple of years old - makes really nice prints on Canon's paper. I don't know what the difference between my printer and the Pixma 6700D you're considering is, but so far I've had no experience with fading prints. I like the individual color ink cartridges, and they're all under $15 to replace, except the larger black one, which is a few bucks more.
I've had good luck in the past with Epson printers (as far as print quality goes,) but the cartridges were bloody expensive to replace, and they seemed to orphan models over a year old, making finding replacement cartridges a real pain. I've tossed out two perfectly good Epson printers because I could no longer find factory ink...
I can't speak for HP - haven't used one recently. Good luck with whatever you choose.