Whoa, the BEST Yakuza game?! That's some incredibly high praise! Hard to believe they knocked it out of the park so hard with their first outing with that engine on the PS3. Seems we weren't quite that lucky with Yakuza 6. Well, I'm really looking forward to digging into it, then! Thanks for your insight. Out of curiosity, if you're willing to, how would you rank the games in the series?
The thing that separates 6 and Kenzan in terms of quality I feel was partially due to Kenzan building on what was already in 2, while 6 had to chop out some legacy stuff that has been in the games for several sequels (and following up the juggernauts of content that were Yakuza 5 and 0 certainly makes it seem worse than it actually is). Also Kenzan is a side story, 6 is the end of Kiryu's story so people were way more critical because of that. If the first Dragon engine game was not a mainline sequel or the end of Kiryu's story I bet it would have been more warmly received. Then again, I loved Yakuza 6, its got some of my favourite characters in the series, Takeshi Kintano especially I really loved in this game. Plus the Dragon engine is something I've really taken to (I love the added immersion it gives me when exploring the city) plus its got some fantastic set pieces and side stories - it just needed another year to bake in order to get it to where it should have been. Well, that and there is one plot point I'm not a fan of, but that's spoiler territory so I'm shutting up now!
Your millage may vary with Kenzan, but I just loved the change of setting, the characters, the combat and some of the side stories used in the game (one particular holds "best of series" status in terms of the humor). I really need to replay it sometime to see how it holds up now, especially with Ishin being so good as well.
I'm not much for rankings, my opinions on the games change so much. For example the more I think about Yakuza 3 the higher I rank it in my mind, on replay its become one of my favourites. While Yakuza 5 (one of the more divisive entries) is probably top 3 in terms of gameplay for me - just because I loved getting the 100% so much.
Content wise I'd probably give the top 5 games to: Yakuza 0, Yakuza 5, Yakuza Ishin, Yakuza Kiwami 2, Yakuza 6
0 has a nicer spread of content, but 5 just has a shit ton of content. Ishin has a nice different variety of content (not counting the completion lists which were just a grind). Kiwami 2 and 6 have a really nice variety of content, and 6 especially has to get mentioned for the following reasons - snack bar conversations, "fishing" (aka lightgun spear fishing!), the entire Sega arcade (VF5 FS, Puyo Puyo, retro games etc.) and some nice refinements to existing mini games (bar darts). Kiwami 2 has a slightly worse arcade, just because it has less games but makes up for it by bringing back way more mini games missing from 6.
Story/characters wise its basically:
Kenzan=0=2, 1 (Kiwami), 3, Ishin
4 isn't listed because for the life of me I forget most of it. Kenzan was amazing back in the day so I rank it all the way up top, but both 0 and 2 are amazing as well - 2 has the weaker story (it has some really baffling plot twists) but has amazing characters - Kawara, Karou, Ryuji are all top tier characters and the Majima usage in the game was just right. 1 will always hold a special place with me because its the first game and I loved the Kiryu/Haruka dynamic in it, plus it has a ton of amazing characters like Kazama, Nishiki, Shimano etc. Kiwami makes the story better thanks to the added story scenes. 3 and Ishin are both quality stories with some amazing set pieces late in the game, however both take a time to get going. 3 also has a few really odd plot twists that I'm not a fan of, but really I have to mention it since I love the second half so damn much.
Only thing I'm not clear on, is if I'd put Kiwami 2 up there with Yakuza 2 story wise. Its basically just because a couple of story scenes get some music changed and makes the scenes less impactful. Gameplay wise its better than the original, but those original scenes were better audio wise than the new ones... This might end up as a moot point by the time the game gets released in English though as the music in these scenes will almost certainly be changed again so who knows.
So basically my rankings are pretty pointless, as I love each and every one of the series (yes, even you Dead Souls!). Its basically one of the most consistently great game series I've ever played.