I worked as an HP sales rep, (and an Epson rep before that) and I've seen a lot of photo comparisons. Mind you it's been over two years since I did this, but I hope this helps:
a) There are really no bad printers out there. Still, I'd avoid Lexmarks. Their quality several years ago was atrocious, and I've heard too many customers complain their Lexmarks died after a year or so. With the possible exception of Lexmark, print quality of all photo printers is basically the same, which is really good. Any differences are irrelevant to practically everyone, i.e.: you won't care about any differences.
b) When Epsons work, they seem to be kick-ass. BUT, you need to be using them all the time, otherwise the nozzles clog. And everytime you start them up, they "blow their noses" to clear out their nozzles. I've heard from customers they go through ink like crazy due to that.
c) HPs have this nasty habit (at least up 'til two years ago) of leaving trails of little white dots where rollers contact the printing surface. How noticeable are these trails? All owners eventually notice it. I lost a few sales thanks to them. Still, HP cartridges are sealed, therefore, you can let the printer sit there for months, and your ink won't dry.
d) Next photo printer I buy will be a Canon, only because I've never heard anyone really rage against their Canons like I did with the above brands. Their ink is the cheapest per page, according to manufacturer claims. (It is virtually impossible for lay people to test actual output). My one concern is the interface between cartridge and printer--it's a pad. Unless they've changed it, these pads let the ink dry out the fastest of all four manufacturers.
Just remember: the human eye can't even discern the quality improvements being made these days. And if you can--do you care? The benchmark many people use are photos they get from a traditional film developer. As far as I'm concerned, all photo printers do a better job.
There are other concerns too:
a) speed. Personally, I've never been in such a rush I NEED to print my photos NOW. I still like the anticipation of going to the grocery store to pick up my pix. But if it's a concern, a printer that separates the cartridge from print head is faster. (Moving just the print head is lighter than moving the print head + ink).
b) cost. HERE'S where I dispute manufacturer claims. Since I worked for HP, I can dispute their claims; but I'm sure it applies to all manufacturers. They made claims their 57 cartridge would crank out something like 75 4"x6" photos in their photosmart 145 printer. MY CO-WORKERS SAID THEY GOT THIS KIND OF OUTPUT. I N E V E R did. NEVER! I would get about 25, then one colour of ink would run out, and the next 10 pix or so would be increasing levels of paleness. So, at the time, we were talking about 1.50CAD to 2CAD per photo--just in ink costs. Imagine: one cartridge would only print about 3 (to maybe 5, depending on the photos) 11"x17" photos.
c) I understand, (but have no experience with), newer colour laser jets give some pretty good photo quality. That may be, but during my time, laser was absolutely lousy for photos.