So since Yakuza 0 just came out and seems to be hella popular compared to the other games, let’s talk about the series!
Please remember that if talking about Yakuza 0 its best to tag it behind spoilers for a bit! Game just came out and its worthy to discover by itself, really.
I’ve been a huge proponent of 5, but 0 has drawn me in moreso than the rest of the series… I don’t usually do side quests, but I had to make myself put down the controller after playing the disco minigame for an hour straight. I got into the games because they feel like super HD PS2 games and 0 nails that feeling pretty well.
I’m pretty excited for it tbh. My fav Yakuza games are 2 and Kenzan*. I fell off a bit after that, I couldnt really get excited for 3, (or maybe I was just full up from playing the previous entries in the series?) and as the series as gone on the cut-scenes get longer and more melodramatic, and there is less a sense of ‘being in a place’ and more moving from scene to scene to progress the story, imo. The last one I played was 4, so it might be that 5 already addressed some of these things?
0 does seem pretty hype though! Everything I’ve seen of it from screen-caps on twitter to giantbomb’s quicklook makes it seem like a return to form – or maybe there’s just been enough time for me to get a hankerin’ for a new Yakuza, either way is probably good and fine. 
*I can’t read japanese, so to play the game I used a FAQ and Egomaniac’s Let’s Play to figure out what was up and where to go do the things that were up.