Gonna have to disagree about the Dragon Engine combat. Setting aside Judgment for a moment, Kiryu's combat in Kiwami 2 (I'll ignore 6 as that's so undercooked combat wise it feels unfare to compare) to both 0 and 5 there's less to be had.
In 5 Kiryu has an insane amount of moves available right off the bat - both heat moves and normal combat moves. This only improves more and more as you play, basically whatever instance you find yourself in, you have a heat move to handle the situation. Then 0 changes things up with giving you 4 distinct styles all with their own heat moves, counters and own traits (want to dash/dodge more like Akiyama? Rush, want to have Saejima level tank power? Beast etc.) and again, it feels so darn good to use, especially in the end finale where you can swap between them and destroy hordes of enemies.
Kiwami 2 just has less moves. That's all. Gone are 0s stances, with a couple of moves here and there rolled into Kiryu's main style (some beast traits remain for example). He's slower and less agile for sure, and everything definitely has more of a weight to it - in and of itself not something I hate, couple that with the physics engine used now and it can lead to some awesome moments. Tiger Drop absolutely sucks though and I don't recall Kiryu ever getting his R1+circle counter back from Komaki (can anyone confirm? I can't remember 100%)
Its not so much I don't love Kiryu's combat in Kiwami 2, they corrected almost all the issues I had with 6 (mainly just weapons and moves that were missing) but when you take his recognisable fighting style from 1-5, and his badass stances from 0 and compare that to his smaller moves list in Kiwami 2, I can't agree that its better.
Now Judgment, that's a different story because Yagami has his own brand new moves list, so the expectations of 10 years of Kiryu combat isn't there. Plus he gets his own flips. wall bounces and other crazy stuff that really helps not only set him apart from Kiryu, but also breath some new life into the combat - especially against larger crowds. He's also got even more heat moves (tons in fact) and his tiger drop is fixed over the last two games. Yay! And two clearly defined attack stances. And so many context sensitive heat moves against both solo and crowds that combat rarely got boring for me. Honestly, the only negative I really have over this combat is some larger enemies/tigers are a pain to hit, as you kinda "bounce" off of them on hit, it just does't feel quite right. Judgment definitely sets the benchmark for DE combat, its the one sad thing about 7's combat change, as undoubtedly we'd have seen Ichiban with his own style(s) and moves built up from the experience of the past 3 games, though the new combat ideas could introduce their own legit epic moments, we'll have to wait and see.