So I finished Yakuza 6 last night. Overall I was quite impressed with the game, the engine, the game play, and of course the story. As a preface, the story arc of Kiryu and this series in general you can't take too seriously. Like any video game, I think the writers were left with a few realistic outcomes. I won't spoil it, but I'm satisfied how the game ended. The main villain is downright dastardly and I hate him. Most of the villains in the story you can definitely see where their motives come from and are usually honorable, but Tsuneo Iwami is just a horrible human being. I also loved Kiryu's ultimate punch to Kanji Koshimizu's face.
I'm at peace with not being able to play as Kiryu as a protagonist again, and this will let me replay any of the PS4 remasters with the full enjoyment of playing through them once more. I'm also looking forward to Fist of the North Star and Judge Eyes / Project Judge.
Overall, here's where I'd rank the series from the Western Releases. As a caveat, none of these games barring Dead Souls is anything less than an 8.0/10.0 for me. They're all pretty fantastic in their own right.
Yakuza 0
Yakuza 6
Yakuza Kiwami / Yakuza
Yakuza 2
Yakuza 3 (Revelations are the best)
Yakuza 5
Yakuza 4 (I love the introduction of multiple playable characters)
Yakuza Dead Souls
*Yakuza Kiwami 2 is on my soon to play list.