What cut of meat for hamburger?

For those out there that are grinding your own hamburg, I have a simple question.

What cut (and why) do you use to make your hamburg??

I am looking for the "general purpose" hamburg here, not hamburg you may grind for some special dish.

I have tried a couple different cuts, mostly the bigger chunks from Cash & Carry, that actually have multiple cuts included.

Just curious to know, so maybe I can try that cut/chunk in the future.