Got into chapter 6 on Y zero and man is this one hell of a game, I wouldn't say it has the bet side content, I've done much and while the entertainment spots are a nice touch many of them are implemented too blandly, only a few are extremely fun and as for the side quests they are the same as Nier Automata, only having that narrative pull. Not to say this game isn't great, it's definitely up their with GTA5. Great game though, thank you for the recommendation, I think I'll skip Kiwami and 6 cause I doubt they'll top this. Hopefully they'll out a new Yakuza before the next console reset.
Glad to hear you're enjoying it. It is a damn good game. If you're on Chapter 6 then you're getting into the good stuff now. The scene at the end of Chapter 6 for example is pretty intense.
How much of the side content someone ends up liking depends on the person, so rather than saying best I agree with how the guy in the video worded it, that "the amount of effort and care they put into it is second to none". You still have more unique side content to discover as you play on. Not just more narrative focused ones, although some of those are good and that's fine. But I mean more side content with unique game mechanics. One becomes available in Chapter 6, although I don't remember how much of it you're given access to on your first visit there. (It's the area behind the big door that the rich guy tells you about.) Another becomes available in Chapter 7 that only Majima has access to. Etc.
Some of these I spent quite some time on. So keep playing and see how you feel by the end of the game.
A few side quest related questions though, without spoiling anything.
1.) Have you met a chicken?
2.) Did you watch any suspicious movies?
3.) Did you try the telephone game?
I agree with you about not expecting Yakuza 6 to top this game, mainly based on the story. It's interesting that you feel that way already though. Then you'll probably feel more strongly about that later. But I'll still play Yakuza 6, and Kiwami 2 (you might want to play Kiwami 2 as well for a specific reason after you finish Yakuza 0. If you end really liking the game, that is) because if they're half as good as Yakuza 0, I'll still enjoy myself, and I want to see how this story ends. And Yakuza 6 is the end of Kiryu's story, Sega said.
Kiwami 2 will use the new engine from Yakuza 6, so that's a plus as well.
As for Kiwami 1, you can tell that they weren't quite as good at the writing portion back in the first few games as they are now. And there was one particular character and his development that fans had a hard time buying in the original, so for Kiwami they added some new scenes that would better explain why this character changed the way he did.