What is your favorite romantic movie or movies? Why what makes them stand out?

Sense and Sensibility, adapted from the Jane Austen novel, was surprisingly good.  It's one of the few romances that considers a guy's perspective, although it's mainly from a woman's view.

Eternal Sunshine of a Spotless Mind is incredible at depicting what goes on in a lot of modern relationships.  It's a unique and quality film that doesn't follow the typical romance format.

Shall We Dance (Japanese remake) does a excellent of telling a story about a man who has an secret affair by taking up ballroom dancing, after finding himself becoming attracted to a young dance instructor.

Actually i liked Enchanted with Amy Adams. Funny,romantic and good animation.

I liked "Notting Hill", because the OTHER side characters, actually had some development and back story........and their stories were just as interesting as the main story .

"Love, Actually" was also quite Good.  As it had a bit of happiness and sadness,  which is more like true life....and sometimes, things   don't work out, and life isn't always a bed of roses,   so that was a tad more real. 

Romantic movies are often formulaic: a geek attracted to a popular student, there's a bet involved, the ruse is found out, everything turns out well.

To me it has a lot to do with the chemistry between the leads. Good examples of this are:

How to Lose a Guy in 10 Days (great chemistry between Kate Hudson and Matthew McConaughey, they can't help smile in the presence of the other).

The Holiday (great chemistry between Kate Winslet and Jack Black/Cameron Diaz and Jude Law)

The first one that comes to mind is "When Harry Met Sally."

Besides the writing, direction and performances by the lead and supporting cast, I also like how it spans the course of 12 years and is anything but a youth-oriented "love at first sight" story.

Harry and Sally are complete characters who have lived their lives, established careers, made lasting friendships and have been madly in love with others.  Their first meeting is tense...even borderline hostile.  They barely spend any time together in the first 10 years of the movie's timeline.  Yet we watch them grow and evolve in characters and, each time their paths cross, they grow a little closer to one another.

The movie's timeline and the little vignettes of older couples recounting their first meetings shape the movie's central view of love:  True love is not something that suddenly happens, nor does it remain the same year after year.  True love is the entirety of the relationship.