Dont really have a single favorite, so Ill just list a few.

Quentin Tarantino - Inglorious Basterds
Wes Anderson - Fantastic mr Fox
Dennis Villenueve - Blade runner 2049
John Carpenter - The Thing
Steven Spielberg - Jaws
David Fincher- Seven
Stanley Kubrick - The Shining
Francis Ford Coppola - The Godfather part 2
Christopher Nolan - Inception
Damien Chazelle - Whiplash
Akira Kurosawa - Seven Samurai
The Coen Brothers - Fargo and NCFOM
Sergio Leone - The Dollars trilogy
Peter Jackson - LOTR trilogy
Scorsese - Goodfellas and Departed
PTA - There will be blood

Several others, but thats enough for now 

Lot of great calls here! Spielberg, Tarantino, etc are among my favs as well.

Being a massive kaiju nut though my fav is a bit niche; guy named Shusuke Kaneko who did a lot to modernize the giant monster movie in the 90s and 2000s, and also did some other nifty Japanese sci-fi/fantasy flicks like Pyrokinesis and first two Death Note films.

His best is probably Gamera 3, still one of the genre's benchmarks nearly 30 years on.

Hm, can't say I have favourite...I used to say that Apocalypse Now by FFK is my favourite film, but it's been a while since that. So...

Overall - I'll go with Hitchcock
Most creative - probably Kubrick...or Kurosawa
Most versatile - Spielberg...or Wilder
Favourite that's still making films - Wes Anderson
Favourite off beat - Jim Jarmusch
Favourite duet - Coen brothers

A lot of great answers, but Guillermo del Toro isn’t getting the recognition he deserves.

I think these are the ones i consider my personal favorites

Francis Ford Coppola - Apocalypse Now
Christopher Nolan - The Dark Knight
Peter Weir - The Truman Show
Milos Forman - One Flew Over the Cuckoo's Nest
Ridley Scott - Gladiator
Frank Darabont - The Shawshank Redemption
David Fincher - Fight Club
Quentin Tarantino - Pulp Fiction
Stanley Kubrick - Dr. Strangelove or: How i Learned to Stop Worrying and Love the Bomb
Steven Spielberg - Saving Private Ryan
Orson Welles - Citizen Kane
Guillermo del Toro - Pan's Labyrinth
Brian de Palma - Scarface
Peter Jackson - LOTR: Return of the King
Danny Boyle - Trainspotting

i'm also really shocked no one has mention David Lynch so far and I think his magnum opus would be a tie between Mulholland Drive and Twin Peaks

Tarkovsky - Mirror
Bergman - Fanny and Alexander (long TV version)

Great director; Pan's Labyrinth and Pacific Rim are among my favourite films.