As I think has come clear in many of my musings on Dracula, I'm a man who values fidelity to source material. Unfortunately, Stoker's original novel has only seldom received film adaptations which were in anyway faithful to the novel, this in despite of the dozens of pictures which have been made. My pick for the most authentic adaptation is the 1977 BBC TV mini-series Count Dracula, directed by Philip Saville and featuring Louis Jourdan as the titular count.
Now, I should be up front, this is not a truly faithful adaptation. As per usual, the most obvious telltale sign is the presence of Quincey Morris; this time, he almost made it, instead merged with Arthur Holmwood into one character. It's appropriate as Holmwood is the second-most frequently omitted character.
The little bits and pieces from the novel which don't normally turn up in film adaptations - such as Van Helsing pressing a communion wafer into Mina's forehead - caught my eye. This may not be the best adaptation of Dracula production-wise, but it is quite faithful and that goes a long way towards satisfying me.