I'll add four for starters. They have in common that I found the characters believable, the acting so natural that it didn't strike me as "acting," a great story line that I could identify with and four great performances:

Tender Mercies with Robert Duvall
Trip To Bountiful with Geraldine Page (who won an Oscar)
To Kill A Mockingbird of course, with Gregory Peck in perhaps his finest role
Harry and Tonto, the best "buddy" road movie co-starring a cat

The first three movies have something else in common. The screenplay was by Horton Foote.

Jerry