I don't completely agree, but the arguments are subjective and each has his preferences, for color printing. You can get great prints from Epson, HP and Canon. Turn to black-and-white, however, and HP takes the cake. If you are printing a lot of black-and-white (I do), the HP z3100 is the clear choice. The z3100's use of only gray and black inks, plus the gloss enhancer (not found in any Epson's I've used), enable one to produce the first digital B&W's that are at least as good as traditional B&W darkroom prints in a production printer. B&W's on the z are free from metamerism and the gloss enhancer has eliminated gloss differential. I have printed the same B&W file on the z3100 and the Epson 7800 on any glossy / satin paper, and it's not even close, the z is a B&W photogs dream come true. Also, been printing with the z since May and still not one clog.
People who are shopping really should just go and have their files printed on the models they are considering. That's the only comparison that matters. If one prints mostly color images on matte papers and already has a profiling system or canned profiles are adequate, one can safely stick with Epson (I haven't used Canon), although I moved away from Epson because of clogging issues with every Epson printer I used over the last 7 years. If one needs to print on matte and glossy, needs good profiling, the z deserves a serious look; and if one prints a significant amount of serious black-and-white I think the z is the only way to go.