Best NPC chatter!

One thing that always enhances my enjoyment of games is the ambient NPC chatter.  Really good, spontaneous chatter really immerses you in the experience, making a game feel more organic, less scripted.  Even something as simple as a change in inflection from unit acknowledgement goes a long way towards building the experience.  Relic and Valve are especially good at this, among many other companies.  That said... here's my tops! 

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