What is Ross favorite movie?

You're likely thinking of the character Ross Geller from the TV show "Friends". While the show never explicitly states Ross's favorite movie, he does express a strong affinity for "The Godfather" in several episodes.

He references it in:

* "The One Where They're Up All Night" (Season 1) when he compares his relationship with Rachel to Michael Corleone's.

* "The One with the Holiday Armadillo" (Season 7) when he dresses up as Don Vito Corleone for a holiday party.

So, although not explicitly stated, "The Godfather" is a strong contender for Ross's favorite movie.