For me it's:
1st place - Fight Club - just love everything about it, but i think mostly, the cinematography and production design. I mean, this dirty, wet, but refreshing at the same time mood is just a killer.
2nd place: - Pi - i love weird movies and this is the best and the weirdest movie i've ever seen. Love the directing style in it, very unique.
3rd place - Memento - that movie is genius. How it was made shows real genius of filmmaking. Also the script is just master.
4th place - Training Day - i love how this movie just evolves. I've always liked the idea of movies that were happening in just one day, from morning to night. Also acting is genius and directin is outstanding.
5th place - La Haine - same thing as with Training Day - the one day story. But what really got me is the style - small budget, looks like it could be made by anyone (anyone good), this urban style is perfect.
now you turn guys