Well I'm going to give you a slightly different answer. So for background, my main enjoyment from the game comes from flying FA off and seeking increasing mastery over it. I do power play , some bgs, planet/station hooning in ships and both pve and pvp. I don't do exploration , or mining , nor do i do much trading either, neither float my boat.
I have Odyssey and have given it a good go. But for me, Horizons is the better and the only time I'm in Odyssey now is to collect a squad wing mission payout. I will explain why I think this.
1. Lighting. Odyssey is Dark, it's like they turned it into a DC superhero movie. Yes you can sort of fix it by adjusting the Gamma and HUD brightness, but even then the colours are kind of washed out. And that applies to the ships and suits. I personally prefer the Horizons lighting, so I don't see an improvement.
2. Planet Generation. I fly down to planets to find canyons and ravines to fly through to test the fa off skills. Called Hooning, it only works where the planets have these features and there are quite a few who do this. The new Odyssey planet system has taken out the canyons and ravines and replaced them with a rounded much flatter blamange topography. It's useless for planet hooning. I'm told that they had to do that to enable to new on foot biology details /features to work. So although great for this new on foot activity , it's removed a whole area of game play for me . So I perceive the new planet tech as a negative.
3. The cockpit menus when docked. I find the Horizons version better laid out and more intuitive to use. One exception though is the Odyssey Galaxy Map which is a massive improvement. In fact for me it evens out the other cockpit menu displays, so I will call this a Draw.
4. Stutter /Lag. I fly mainly in VR , have a new PC. In VR, I find Odyssey much more prone to lag stutter issues and crashes (especially around Stations) when compared to Horizons i barley have an issue . I cant comment on that in 2D mode though.
5. The Shards /mat farming. The new planet tech in Odyssey has changed how they appear and scattered them about. They are easier to farm in Horizons.
6. Flight mechanics. Strangely Fdev fiddled with this , I'm not sure why. Its most noticeable in fa off , but the ships fly a little differently in Odyssey. In Horizons the controls are more lively and precise , in Odyssey they seem more sluggish and prone to surges . I've tested it out taking off and landing ( then switching games) and in a few other situations.
To be fair , what Odyssey does give is the Interiors , more landable settlements and FPS gameplay . But these three are all linked. The Interiors are where the main FPS activities are organised. ( But that means if you are not doing any FPS then the Interiors are pointless to leave your ship for).
There are more Settlements for the FPS to happen, but again if you are not doing FPS they are not really adding much to the Space gameplay.
Which then comes to the FPS - be that Combat or Exploration or Infiltration or any of the other options. The key here is if you are interested in doing that kind of gameplay, and that is subjective.
Speaking just for myself, I like elite as a space flight sim. That is the part I'm in it for . I'm not into any FP games (and we have plenty in the house ) . Getting out the ship and using the Avatar to do stuff I've zero interest in ( and I have tried it, I did the tutorials, I did a couple of on foot missions, did a few trips in the new space taxi). But it's not for me.
So when I compare Odyssey with Horizons, it's like I take a scalpel and cut away all of the Odyssey stuff that relates to FPS . And then I compare the Odyssey "original" game play against Horizons and the 6 points above are what I get.
Last year they were talking about merging Horizons and Odyssey, so I'm going to stick to Horizons in the meantime for as long as I'm able.
But if you fancy getting it to check out your FC Interiors and see then new jump , then go for it. I will certainly log into Odyssey and have a look about the FC to check it out, likewise the new jump. If it's anygood I may log into Odyssey just for the jumps and back out again when I get where I'm going .
Fly safe!