This is a really difficult question for me.  I had 
to stop & think for a moment - separate those cels 
that are my favorites from those that are the 
"best."  So difficult, in fact, I couldn't choose 
just one...  (oh, if the pics don't load, hit 
refresh - AOL just sucks as a webserver, gotta 
find a new one...)

First, Vegita from DBZ.  Perfectly centered, 
facing forward, eyes open, with a classic Vegita 
expression.  He's just beautiful...






Next is Joe Higashi from the second Fatal Fury.  
Again, nicely centered, A1/B1.



Oh, & I just had to show off this one.  He may not 
be one of the "best" - he's partially facing away, 
his eyes are closed, half his face is in shadow - 
but I absolutely love this cel.  Joe from the 
third Fatal Fury in one of my favorite scenes:






Larger scans can be seen at my gallery ::points 
up::  I didn't want to suck up *too* much 
bandwidth.  ;-)