I think it's a close call between Tommy and KC Jones, and I think I'd give the nod to Tommy.
KC certainly earned the respect of a half dozen basketball legends en route to two rings, and he certainly had a winning formula. But I would guess that his actual personal contribution to winning was slightly less than Tommy's. The 80s formula of success seemed to be for KC to keep everyone happy and not complicate things by getting in the way. Hey, hey recongized that's what needed to be done, and he did it.
But I'm inclined to give the nod to Tommy because it seemed like he had more of a coaching agenda, molded his teams in that way and won a couple rings in the process. Basketball in general was probably being played at a higher level during KC's years, but Tommy had to compete with a great in-division team (the Knicks) and other great W.C. teams, Bucks, Phoenix, and Wilt's Lakers were around too (though never in a head to head with the 70s Cs).
So, from the standpoint of a coach seemingly "doing more" to implement a winning formula, I'll go with Tommy by a nose, but I'll give KC a big fat TP in the process.