It sounds like you made your choice, but I still wanted to chime in.So for me, I don't really see a benefit for me to play Oddity. Thanks for the replies folks.

As far as I know it, Horizons and Odyssey are running on the same engine in the same universe. The difference is that Odyssey has all the On Foot content, new ships, and some different textures. I think there's a bigger difference between Horizons/Odyssey and Horizons Legacy (HL). HL is on a different engine. It's live, but in a different universe. It doesn't have as much of the MMO kitsch as the current version. In my opinion, it feels more like a space sim and less like an MMO grind. You still have powers, but fewer of them. You still have tons of ships (I think the same as Horizons, but not the ships from Odyysey). My understanding is that Horizons Legacy being preserved in a stable (no updates) state mostly for the sake of console players who are no longer supported with the new stuff. The performance of HL s a LOT better (my rig runs hot with Horizons/Odyssey and cool with HL) so you can run with higher settings. I've read that the VR looks better in Legacy. I would also say that the visuals are arguably better in Legacy. The visual changes with the current engine have had mixed reviews and I find them mostly grating.
There's also plain Legacy which pre-dates Horizons, but I don't know anything about that.
I'm actually playing Legacy for what sounds like similar reasons as you not buying into Odyssey. I have Odyssey, but found the On Foot content to be mostly not good. I don't like the newer visuals and rendering. I like being able to run Legacy with ultra high settings vs. current on medium. I actually like having less MMO-ness to it. I'm not grinding anything for anything. I'm just lackadaisically meandering through a galaxy size sandbox and honing my flight skills in a Newtonian physics environment (i.e. FA off).