I think Yakuza 0 isn't even close to the best, and retcons a bit too much of the plot of Yakuza 1, so Yakuza Kiwami (remake of 1) felt weird to play as they used some new plot stuff from Y0 making it feel less coherent (there's an added cutscene between every chapter showing how a certain character evolved from 0, which wasn't needed in Y1). The original Yakuza 1 felt almost like Die Hard 1 and was very touching yet badass. But having us know that one character too well made his motivations too odd even with the added scenes.
Also, Yakuza 1, 2, 4 and 5 are the best, in that order.
Plus, Yakuza 6 has FULLY VOICED EVERYTHING, even the substories with the text boxes. No more weird typing noise to replace speech.