As of right now, I usually say that my all time favorite is either Network or There Will Be Blood.
However, I am trying to go deeper with this for myself because I noticed so many of my picks were skewing to the 21st century because that is where the majority of my viewing has been. So, going one year at a time, I'm marching backward to try and fill in some of my cinematic blindspots and decide what my favorite film from that year is. My goal is to go back as far as I can and create a Bracket of all the winners then pit them against one another tournament style. I'm calling it my Best Movie Bracket.
The seeding process is going to take forever because I'm doing like a year a month when I'm active and when work gets busy I have to stop, but I've gone from 2017 - 1995 and I'm working on my best of 2018 and 1994 now. You can see my progress at lifeatthemovies.com.