I had D* several years ago, but it was before they switched to mpeg4. I suspect that it's possible that those channels that originate in mpeg4 might look better on D* since there's no transcoding necessary. OTOH, channels originating with mpeg2 might look better on FIOS since FIOS is still on mpeg2 and in that case no transcoding is necessary for those channels. I'm not speaking to compression here and of course that's the wild card in this PQ equation. FIOS either doesn't compress or compresses the least of the available providers.
I can also add the fact that I'm not wild about their DVR. Their whole house 'solution' is prone to issues such as lag.