Pulp Fiction
Although Tarantino ended up making films that I prefer more in his filmography, it's very difficult to insist he ever did markedly better than this.
So much about this movie is so fun and funny, but that humor doesn't take away from the excellent filmmaking at the core of Pulp Fiction. Aura is just so tactile, and the iconic lines in this movie aren't even ruined by their virality (looking at you, Anchorman). In a funny way, Tarantino and Lin Manuel Miranda are spiritually joined by being the worst parts of their own productions. I really cannot fathom, other than.. for one specific reason.. why Tarantino is even in this movie. Samuel L Jackson in the diner at the end of the film is one of my favorite moments across Tarantino's entire filmography.
A classic for a reason