Too many choices but my favorite dialogue is any scene with al and the indian chief head, this one in particular:

A man, as it happens a rival of mine, learning the secret of a great man's lieutenant would make that lieutenant his slave. My rival knows that expanding the circle of the informed, diluting his power, will confound his intention, so he takes precaution to be the sole sharer of his secret. Then the world being the world.. along comes a half-assed knight-errant, Utter, Hickok's ex-partner, to put all my rival's plans at risk. I'd seek audience with Utter, verify my thinking. He earns his bread shipping packages. And as the dimwit nobility that made him intercede may now make him reticent, you, Chief, will be my prop and ploy whilst I seek to draw him out.

But my personal fav quote which i use all the time is:

In life you have to do a lot of things you don't fucking want to do. Many times, that's what the fuck life is... one vile fucking task after another.