Reservoir Dogs.
By far.
The greatest writer of dialogue since Mamet, Dylan and Shakespeare came out firing with both cylinders on his virgin hypnotizing opening scene.
Just a group of cool dudes sitting around shooting the shit about stuff we've all thought about, but never articuclated quite as well as these guys do - the viewer doesn't even know the context - but it doesn't matter - the dialogue and the emsemble acting are THAT good.
And by putting that scene up front, he makes his characters, a bunch of thugs who commit unspeakable acts, LIKEABLE, simply by having us fall in love with the way they think, the way they talk, the way they interact upon their initial meeting.
Where have you gone, Mr. Tarantino?