I wish Blizzard let us choose which login screen we like...
Vanilla-MOP
http://www.youtube.com/watch?v=ujxDdCE6bFU
WOD
http://www.youtube.com/watch?v=Os9-Qui05Y4
While Vanilla, BC and WOD are not very original (in fact it the same Dark Portal Login screen), I always liked WOTLK the most with its snowy environment and Sindragosa flying.
What you guys think?