I would say AC Rogue was the last good one; had a good gameplay loop, combat was still trash since it was based on Black Flag, but the whale hunting was fun, the boss ships were cool, the ship unlocks were nice, and the story/side-quests were manageable instead of the grind that was in Black Flag.

Just wish they would have kept the combat system from AC3 and then I would have regularly gone back to play Rogue a lot more.