I understand that a judgment of quality of tone regarding the Prophet '08 is partly individual, but not entirely. At least, folks are more prone to agree that two Prophet '08s together make a tone that is, well, not so thin-sounding. Taking it from there, I would put my P'08 pair up against an OB-6 any day. That's not to criticize the OB-6, because I really like its sound and would love to have one. I just don't buy into the whole Prophet-'08-is-thin deal, not even in the case of a single Prophet '08. In my opinion, it's more a matter of one's programming ability than the nature of the instrument. And as a prudent rule, one should never judge a synthesizer by its factory programs. Those are meant generally to show off the instrument's complexity, rather than its character.
There's a new Tetra thread over on the Moog Forum in which the Prophet '08 sound is shredded without mercy. I was always a fan of the "Moog sound" myself, but my Moog ear has always been impressed with the Prophet '08 sound as well, so I don't believe they're so far apart. It's a reminder that all forum opinions - including those of the experts - should be taken lightly. Often, you have to swim against the current to find what's good. And it's generally best to follow a school of thought, rather than a school of fish.