I asked this question in the other thread, but had no responses (has everyone got me on their ignore list? ) ) - how different is this to AC Origins? I'm currently playing through Origins and absolutely loving it (even though, yes it's repetitive and a bit shallow) - just being in the gorgeous ancient Egyptian setting is brilliant escapism for me. Is Odyssey similar?
Yes, it's relatively similar to Origins, but Odyssey has more to it though. The map is far larger and also more diverse than Origins for a start. It's also really beautiful in parts and personally I think that it looks better overall than Origins. That being said though, I do personally use a reshade as I think that the contrast and saturation are too much by far. The world itself though is incredible. Given that you mentioned that you like exploring..well, you'll really enjoy that aspect. In terms of the Whole 'historical tourism' angle it's pretty much unmatched and a step up in scope from Origins in that regard (in my opinion).
The combat is also definitely better in Odyssey, with more variety of moves and a skill tree that has some pretty good skills/combat moves to unlock. You also have naval combat in Odyssey with your own ship, so there's that too if you like that sort of thing. The naval combat is basically Black Flag with spears.
Customisation is also better overall in Odyssey, with you being able to mix and match bits of different armour (of which there is a much larger variety than Origins) and there are more weapons too.
Quest wise, there are far more in Odyssey, but for the most part they're "go here, kill this guy" with no individuality whatsoever. Even moreso than Origins.
The game is also grindy as all hell, to the point where there was a controversy over it on launch. Even though I enjoyed the game I ended up using a trainer towards the end. Not because it was difficult, but simply because I was sick of the constant resource/money-gain grind by that point.
Story-wise Origins is better. If you're looking for good writing, then Odyssey is not the game for you. The writing is utterly nonsensical shite on a regular basis. As storytelling in general, it's shite. Few Assassin's Creed games have had good writing, but this is far below even other titles in the series. The protagonist (I chose Alexios, so can't comment on Cassandra) also has all of the charm of syphilis. I quite liked Bayek as a character. I'd occasionally let Alexios get killed just to watch him die.
Both are decent games with their pluses and minuses. If you like one you'll like the other and if (going by your post) the major drawcard for you is existing within a game world set in an ancient time, then you'll probably love Odyssey, regardless of whether you've just played Origins. Non-spoiler world video:
https://www.youtube.com/v/C8q6j6GeElY