Cels Forum

I was just wondering whose autograph on a cel would be the most
valuable. When I go to Japan this summer, I plan on visiting
a friend of mine who works at AIC.  He is the director(and I
mean head cheese director, not just art director, music but 
the whole enchelada) of many prestegious AIC works:
Gal Force 2		assistant director
Bubble Gum Crisis	director for #4
Explorer Woman Ray	assistant director
Sol Bianca		story and director
Tenchi Muyou		story and director for #1-6 OVA
El Hazard		story and director for #1-7 OVA
Pretty Sammy		story and produce
Battle Athletess		story and produce
Bubble Gum Crisis TV	director

I may also have the opportunity to meet with several seiyuu.
Which of course, brings me my question(aside from the character
designer which people seem to already have established as the
most valuable.) 
Whose autograph would be worth the most?