This was exactly my conclusion also. I've never 
seen even two seconds of any Gundam series, so I 
can't comment on which cel shows his *character* 
more, but I know we're talking about a pilot 
here. In that case, if I were collecting cels of 
him, I would want something showing the cockpit 
around him. In this case, the seat. And being a 
seat, it nicely grounds the image.

But the big reason the other doesn't call to me 
is the symmetry. Centering is good, and although 
people have commented on the "lean" in the image 
on the first cel, you'll notice that the most 
important part -- the face -- is still nicely 
centered in the viewing area. The second might 
have overall better (more complete?) centering, 
but symmetry just has a way of making everything 
look flat. It's not as interesting to the eye.

I also second the notation about the highlights 
on the faceplate, though I hadn't fully considered
that beforehand.

Many Sharp Smiles,
--Drac