Manhunter
I can't fairly rate this movie, so I will skip the score part. This movie is flawed to a degree that will annoy quite a few people, but this is not a problem solely because of my admiration for the director's style.
The cover of the blu-ray says that it is "the movie that introduced the world to Hannibal Lecter", but, while Brian Cox's performance is impressive, the movie is not really interested in Hannibal Lektor. The parts where the movie describes the main criminal Francis Dollarhyde is boring and seriously flawed. His character and action are all cliched; an abused kid grown into an irredeemable adult (as in Will Graham's own words), trying to be loved by women by killing them and controlling them on his own. Even the style of describing him is cheesy. Plot points are boring, cinematography is somewhat predictable, and they are usually helped by licensed songs, which are clearly outdated and distract viewers. Even Hannibal Lektor is merely a side character here, giving him only a fraction of screen time that is not enough to impress viewers. If you are a fan of The Silence of the Lambs or Anthony Hopkins Lector, this movie is not for you.
That said, you kind of knew this if you know Michael Mann. As you might expect from a Michael Mann film, he is not interested in psychopaths. His cinema is all about self-destructive professionals that goes too deep into their own work, and in this regard Manhunter shines really, really bright. William Petersen as the protagonist Will Graham is downright fantastic. He is an extreme case of workaholic Michael Mann protagonist that had went crazy and is again on the verge of being so because he investigates psychopathic criminals by sympathizing with them. Throughout the movie he struggles to use his method while trying not to go crazy for the sake of his family, which results in the fact that every single shot with Will Graham is downright fantastic. All of this is supported by signature style of the director; the fast rhythm of jargon-filled dialogue between Will and his colleagues (including Lektor), the low-key, color-bathed cinematography that adds to the atmosphere, heavy electronic music that emphasizes his triumphant moments, all adds to the depth of his character, that it is no wonder William Petersen had hard time getting out of this character.
You kind of chuckle when the first line of end credit is "A Michael Mann Film", because there is no way mistaking who made this film. If you like his works, in my opinion, his works from 80s are must-watch. They are flawed, but the style is definitely there and way more extreme than they are now, that it's just fantastic to watch those moments even with all the flaws.
P.S. As many have noted, the final shootout is very badly edited for reasons I don't know, so if you are coming from the director's later works, keep that in mind.