I mean kazuya is exactly just a 50/50 machine. Sure he is difficult when it comes to hands, but he is certainly one of the easiest characters in the game when it comes to the head.
Jin/DVJ are better characters to practice fundamentals with if you still want to spam ewgf. But DVJ still has that get out of any situation noobkiller u4 and his 50/50 card.
BUT if you are not planning on becoming a high level tournament player, just play whoever. Its way too common for non competitive players to worry about their fundamentals and burn themselves out with the game, when they dont even plan on competing.
Edit: In this context fundamentals dont mean just learning the basics of backdashing, sidestepping or poking. But really focusing on, and perfecting them for hundreds and thousands of hours.
What on earth would be difficult part with kazuya if not the mechanics?
SOMTHING NEW SOMETHING NEW
forget about tiers and shit, tekken 7 is already pretty balanced, competitive tournament play is the only time when tier whoring matters, but then again, we saw rangchu win with panda against knee in twt.