I will start off after Winged Shadow's and Nessa's post by stating my preferred types of films and following up with my top 20 favourites that I can think of, and then fit those into the categories.
Categories I like (In no order): Western, Sci-fi Thriller, Epics, Period Pieces, Action/Adventure, Drama, Comedy/Cartoon
That covers most I guess minus chick flicks, which for the most part I don't like (some I have been okay with).
= I typed out a no-particuar-order list and have now grouped them so there's no need to read my list twice.=
What I can think of (at this exact moment) as my somewhat definitive top 20 favourite movies ever list, grouped (you make up the name for the group):
Ben Hur, The Mission, The Passion of the Christ, Schindler's List, The Seven Samurai (criterion)
Alien Quadrilogy, 12 Monkeys, The Matrix
The Lord of The Rings (PJ), Back to the Future trilogy
Monty Python & the Holy Grail, Aladdin, The Mask
Lonesome Dove, Once Upon a Time in The West, Unforgiven
Brotherhood of the Wolf, Vidocq
Eternal Sunshine of the Spotless Mind, Suspicion
So if anyone connects with most or all of the movies in a particular group of my list, then it'd be a connecting thing and it'd be interesting to see what you have for your favourites of that same group, I'll probably like them too. The obvious weak point is the sci-fi adventure movies like The Lord of the Rings, Star Wars etc etc, those that most on this board like more than most other movies. So it's not like everyone connecting in that group means anything special.. we're all interested in that genre to some degree!