To compare features and specifications, you can do it yourself. There are enough informtion on their websites.
For sound quality, it gets difficult because unless you audition each of them in the same listening environment, using the same source and the same speakers, it will be tough to tell which one you like best. You may like the sound of one over the other only because of the other components, room acoustics, and perhaps even the settings of the receiver. If everything had been equal, you may actually like the others better.
For these reasons, I find it almost impossible to compare the sound quality of different units unless I bring all of them home. I based my last purchase decision on features, specifications, reviews that include lab measurements, and then I auditioned the ones that I would consider in the dealers H.T. room with my own CD/DVD that I am familiar with. I did my auditioning in more than one place in order to hear how they sound with different speakers.
