I'm not even going to look at the list hahaha....
this is going to be very biased because I love Tarantino...
So automatically it has to be "Kill Bill Vol 1"... I'm sure there were better movies released that year but I just love Tarantinos style and his humor.

The movie i would like to see from 2003 is "Once Upon a Time in Mexico"... I want to watch the other 2 in the Mexico trilogy first though.