LBZ's are by far the best. LMM's are also solid, basically the same thing, but you have some extra emissions to deal with (DPF).
I don't know how anyone could say that the LB7 is the best. Injectors go every 100k miles or less, and the 5 speed trans is garbage if you add any extra power from what I have seen. Don't take offense, I love LB7's and if you wanna do so some work to them they can be awesome. But, for a starting point and considering all generations in stock form, they do not compare to LBZ or LMM. That being said, you will be able to pick up an LB7 at a much better price.