For the purpose of this topic a movie series is a set of movies with three or more movies.

What makes it your favorite?

Some sample series:

Alien
The Hobbit/LOTR series by Peter Jackson
Godzilla - all or a specific era
Hellraiser
Iron Man
Batman
Superman
Gamera
Planet of the Apes
Robocop
[REC]
Hannibal Lector
Indiana Jones
Star Wars
Star Trek
Transporter
Beverly Hills Cop
Bourne
James Bond
Crocodile Dundee
Final Destination

To me what makes a movie series good is when you binge watch and all the movies seem to fit together into one long uninterrupted story.

LOTR and Harry Potter Series, I guess I just like those kind of genre, fantasy, a whole different world

Back 2 The Future

The Land Before Time

Indiana Jones "Kalima"

Star Wars. Lord Of The Rings was great, but the book was so much better. Before anyone says there were three books, Tolkien meant it as one book.

Back to the Future. I was a teenager when all that started. The Lord of the Rings. I read all of those books 3 times (including The Hobbit) before the movies were out. It was a long time to wait.

Predator
Fast & Furious
IP Man
Bond
Beverly Hills Cop

I enjoyed the Star Wars Trilogy before the dark times...

Before Jarjar Binks.