I couldn't make heads or tails of your groupings until I read a little further into the posts.  I was scratching my head because I thought that the movies within each group had some commonality.  I kept asking myself what does Hero and The Godfather have in common or what theme is similar in both Wallace & Gromit and Brazil?  I like your list although it wouldn't be anywhere close to mine, however that's what's good about it.  The differences between us all makes life more interesting.

" @Romination said:

" So Group A is better than Group B to you, etc? I see. Goodness, boy, you got some timeless classics (Godfather, Taxi Driver, Evil Dead) in with some pretty off-the-wall things (Dog Soldiers, Wallace and Gromit, ...Evil Dead).  Somehow this makes your list a lot more likeable than everyone who has just Citizen Kane, Shawshank Redemption and The Godfather (ie  the usual suspects) on theirs. "

You gotta admit though The Shawshank Redemption was a damn good movie and it deserves to be on people favorite movie lists.  Also, I too love The Evil Dead. Evil Dead 2, also great. Army of Darkness however I would be perfectly fine never watching again. It was OK, but I don't get why most people think it's the best of the 3 movies. "

" So Group A is better than Group B to you, etc? I see. Goodness, boy, you got some timeless classics (Godfather, Taxi Driver, Evil Dead) in with some pretty off-the-wall things (Dog Soldiers, Wallace and Gromit, ...Evil Dead).  Somehow this makes your list a lot more likeable than everyone who has just Citizen Kane, Shawshank Redemption and The Godfather (ie  the usual suspects) on theirs. "

So Group A is better than Group B to you, etc? I see. Goodness, boy, you got some timeless classics (Godfather, Taxi Driver, Evil Dead) in with some pretty off-the-wall things (Dog Soldiers, Wallace and Gromit, ...Evil Dead). 
Somehow this makes your list a lot more likeable than everyone who has just Citizen Kane, Shawshank Redemption and The Godfather (ie  the usual suspects) on theirs.

For some reason when I saw Oldboy in group A, it made me think of Old Greg.

I am an advent movie collector, probably more than I am a gamer.  There is no way I could possibly pick my favorite movies in prefect order so instead I have decided to try and place them in my favorite groups. It may be more confusing than beneficial to some, but I feel this is the only way I can sort them out in my mind. Enjoy!
 
Group A:  
Glengarry Glenross
Oldboy
There Will be Blood
Taxi Driver
The Killer
 
Group B:
 Leon The Professional 
Cure (1997- Kiyoshi Kurosawa)
Way of the Dragon
Dog Day Afternoon
Indiana Jones Raiders of the Lost Arch
 
Group C:
The Cat Returns 
The Godfather
Hero
House of flying Daggers 
Apocalypse Now
 
Group D:
Samurai 7
Dog Soldiers
Audition 
Triad Election
A bittersweet Life
 
Group E:
The Exorcists
Running out of Time
Snatch
Enter the Dragon
Pulp Fiction
 
Group F:
Heroes of the East (a.k.a Shaolin Vs. Ninja)
36th Chamber of Shaolin
Evil Dead 
The Wicker Man (1973)
True Lies
 
Group G:
The Thing 
Brazil
Speed
Wallace and Gromit: The Curse of the Were-Rabbit
Memento
 
Group H:
Sparrow 
The Texas Chainsaw Massacre  (1974)
Alien 
Battle Royale
Face/off
 
I would say that the final three or four groups could really be interchangeable for the most part. I just didn't want to end with just a bunch of "honorable mention" titles.
This is not a list of  "This film is the best movie ever created becasue I said!" These are movies that I would place together for my own personal love of them. If it was a list of "these are the greatest films ever made" then I would have probably placed Samurai 7 near the top 3 and films like Snatch probably wouldn't even be on it. Thanks for reading!