I have a Canon Pixma MX300 which was fine until a cartridge broke inside it and now I have to perform surgery on it to get it working with colour printing again. The actual printer/scanner/copier/fax are all great, it's a shame that I broke it.
I think it was actually my own fault for stuffing the cartridge in too strongly.
I have never got along well with HPs. The Deskjet F4280 seems to work ok but lacks features, and some other models have had really awful drivers for the Mac side. I spent hours trying to set a friend's Deskjet 3550 up recently and had to eventually admit defeat - it worked in the most basic interpretation of the word, and the drivers were built in nicely to OSX, but there were persistent setting problems which you couldn't change and it was neutered on features compared to Windows side. Very disappointed.