Not ashamed to say I have been playing AC iv: black flag and AC rogue lately. I haven't played any assassins creed games before but I love the sailing. I kinda knew what to expect for the land stuff since I've already played far cry 4 and watch dogs.
Though rogue doesn't have a Caribbean setting, I prefer it over black flag, with the exception of less epic forts and the ost. The islands are much more interesting to explore and I love fighting gangs. The story doesn't have a ton of tailing missions either. There's even a monopoly aspect where you invest in building renovations and later collect dividends in a bank.
It's gonna be hard to play the other AC games without the sailing, island exploring, fleet commanding, and naval combat.