I actually own all three of them, yet I've only completed Yakuza 3, about half of Yakuza 4, and got Yakuza 5 free with Playstation Plus but have yet to even download and start playing it. I also have Yakuza 0 and Kiwami on my shelf, both unopened, lol.
... I need help :(
My tip: play Yakuza Zero, it's a masterpiece. And perfect for newcomers. Or start with Yakuza Kiwami ^^ Yakuza 3 is in my opinion the only mediocre part, all others are great to legendary. I played each yakuza part for about 80-135 hours in my life. Yakuza 6 is DAY 1 of course! < 3 My favorite games are Yakuza 2, Zero, 1 and 4.
Yeah, from what I've been told and read on the ol' internet, Yakuza 3 is the "worst" game in the series, yet from what I remember, I actually really enjoyed it, especially once you rock up in Kamurocho, that's where it really picked up, lol.
See, I'm not really sure where I want to start, I mean, if SEGA actually comes out and says "Look, we're definitely doing a 3-5 collection on PS4" or something, and it releases in the west, along with Kiwami 2 (Have we even had a western confirmation yet?), then I'll hold off for a while and eventually start with Yakuza 0 and make my way through that way, but until that, I'm sort of hesitant about starting right from the beginning, and might pick up Yakuza 4 again and finally finish it, then move onto Yakuza 5 (Both on PS3 of course), AND THEN go to Yakuza 0 and Kiwami... and then Yakuza 6. It's a weird train of thought, but basically I just don't know if I want to play them in numbered order, or release order (3, 4, 5, 0, Kiwami, 6) since if I play them in numbered order, the gameplay will go from being great with 0 and Kiwami to worse with 3-5, to great again with 6, whereas if I do release order, the gameplay will get better and better with each one I play, lol.
... Confusing, right? :P