Major League or The Sandlot for the win, nothing else is close. I'll get shit for saying it, but I don't get the love for Field of Dreams or Bull Durham. Bull Durham is decent I guess, but Field of Dreams puts me to sleep.
For me, its Major League by far in 1st. Then probably Bull Durham.
Third is tougher though, as it could be the Natural, Field of Dreams, or Sandlot. 8 men out is also solid, but just depends on what sort of movies you like. I like the comedy side of my top, in addition to the baseball side.