Like so many others of us I have a hard hard time 
choosing one that is "best".  Favorite? Easy.  
Zel looking over his shoulder (melt).  Nicest 
shots? ummm... Vash, Captain Tylor, Otaru...

But all around best? It's one of the two I have 
in my office.  Background, big emotional moment 
and just perfect composition in every way.  It's 
not even my favorite set of characters from the 
anime, but it's a beautiful thing.