I played both, loved the map in Origins, it was incredibly atmospheric. Odyssey is MASSIVE, same old Ubi with some refinements, the gameplay loop is enjoyable but there is repetition. The world is beautiful as usual and some quests are really nice, better than in Origins. Combat is different, faster and more offensive with more skills. Both games are good, IMO, though I slightly favour Egypt over Greece and the size of Odyssey is somewhat overwhelming (90h in and I've seen a half of the map).