I think for non-atmospheric worlds both are fine at generating realistic enough terrain and only the tech issues make odyssey worse here. For atmospheric worlds with less craters and more flat surfaces odyssey doesn't have enough to be interesting and justify itself and that just brings further attention to the shortcomings of the terrain on non-atmo planets too.As for me, I liked some of the typical Horizons features, but overall I prefer Odyssey. Bodies in Ody looks less sugarcoated (if that's the right word) and more like actual astronomical objects.
Mainly it's the lack of chaos (for example craters being more round than on the real pictures) and the illusion being ruined by the repeating tiles (which is mostly a DSS issue actually). This is more of a limitation of the techniques used probably.
The promise of the tiles - having interesting, highly realistic terrain (without too much GPU work) doesn't deliver - at least on this set of planets which limits it too much. There's some promise in planets with more bio signals that have more biomes and thus more varied terrain mixed with each other, but those are rare and seeing the same tiles repeated everywhere ruins them even on "good" planets eventually.
There's probably quite a few things Odyssey could do to make people appreciate the terrain that's currently there more, but they never tried and seemingly just gave up on it.