Personally I loved the AC Valhalla, AC Odyssey and AC Origins direction and especially the introduction of a secret cult to hunt down and eliminate to reveal a secret bad power house who controls it all. Also generally loved the longevity of those but each to their own.
Agree with this, I enjoyed all three!
First AC game I played was Unity and I really enjoyed it. Thought the world of Paris was dense and really beautifully presented and the story/game was fun. I was surprised to read later on that the reviews weren't great at all.
I tried Syndicate with really high hopes because of how much I enjoyed Unity, and thought it would be fun to play a game set in London. But it totally underwhelmed me and I gave up less than 10% of the way in. Don't really know why, the setting seemed dull and grimy and the constant crappy cockney accents really grated.
Didn't pick up another one until I got Odyssey heavily discounted and it was ace, the map is stunning and was a real joy to explore. Seafaring element was well managed too, never felt that the quests got TOO repetitive, though I was frustrated at how little impact you could have generally on the world around you (ie you could change power in a region but there was no real benefit or point in doing so).
Then played Valhalla, thought it was a bit stodgy in places but the story was great and the game was fun. And just finished Origins (also v cheap on sale) and was surprised to enjoy it more than Odyssey. Really varied map, never felt like a slog.
Having a short game is a good idea so keen to see what that's like. The next big one in Japan is exciting but as mentioned above, it'll be hard to compete with GoT which was brilliant. Do feel that there might be some lesser mined civilizations ripe for Assassins Creed. Something in South/Central America with the Aztecs, Incans or Mayans would be brilliant. Or something in south or southeast Asia.