But they each have big differences in ease of uploading/ordering and image quality. Here are my conclusions after running identical sets of prints through each of the five different processes:

1). Ofoto with color correction
2). Shutterfly with color correction
3). Shutterfly without color correction
4). Snapfish with color correction
5). Snapfish without color correction
6). Mpix black-and-white
7). Mpix with color correction
8). Mpix without color correction

Note: Ofoto does not seem to let customers disable their automatic adjustment.

For people-photographs printed in color, SnapFish and Mpix are, by far, the best. In fact, I'll go so far as to say that SnapFish and Mpix were the only ones of the big four (O,S,S,M) that delivered even acceptable skin tones photographed under anything other than optimal lighting conditions*. 

For non-people photographs printed in color (i.e., landscapes, flowers, and everything else), all four (O,S.S,M) seem to give acceptable results, although Ofoto seems to over-expose the highlights more often then either Mpix, SnapFish or Shutterfly.

For ease-of-use (uploading and ordering), Shutterfly and Ofoto are better than SnapFish, because of their drag-and-drop web tool, and better than Mpix for speed of their webserver. However, only Shutterfly and Mpix displays the file names (all three display thumbnails) when you're ordering size and quantity of each print. This is absolutely critical when you're ordering from a large prepared list of images. They also print the name of the image file on the rear of each print. This is absolutely critical when you pick a print and decided you want to order more reprints. Mpix's website looks good, but can be near-impossible to navigate through if you want to go back and change something in your order. Also, Mpix's cropping tool forces you to keep the crop region within all four sides of the image. Worst of all, Mpix's website can be so slow that it becomes almost unusable. For these reasons (and their outstanding telephone customer service), Shutterfly is my preferred service for non-people images printed in color, although Mpix's color quality is just as good.

For black-and-white proofs, Mpix is the clear winner. Although their custom black-and-white paper is a matte finish, it doesn't have any of the color cast and exposure problems that Ofoto and Shutterfly have with their color papers. I haven't tested SnapFish with black-and-white proofs, yet.

Remember, these are only my opinions.  I have over two years' experience using Ofoto and Shutterfly, and less than one year's experience with SnapFish and Mpix. We shoot with a Canon A80 point-and-shoot, and a Canon EOS D60 DSLR. Half of my shots are adjusted in PhotoShop, the other half are printed without any adjustments. I've reviewed my color adjustments on three different monitors (made by three different manufacturers) before uploading them. For these reasons, I don't believe that the variations between S/O/S are due a calibration problem in my monitor.

* I should clarify that the vast majority of my people-photographs were taken with Caucasian, Asian and Hispanic subjects. The few color examples that I have of people with Afro-American heritage looked good with both Ofoto and Shutterfly. This is to be expected, because (correct me if I'm wrong) Caucasian skin tones are supposed to be the most difficult to accurately capture in color photographs. I don't know why this is, but this is what I learned in a color printing class twenty-five years ago.

Comments? Email me.