I don`t know about best one, because there 
were so many very creative and good ones.
One trigun team looked very the part, but 
actually...I like the sexy girl costumes, (with the 
sexy girls in them) the best, and that is being 
very biased of course..There was this one 
Asian girl that I was especially fond of..err, I 
mean her costume that is (*cough). 
  But I can show you the funniest one that I 
saw that had me in tears! I thought that this 
was either very cute or very sad...that is why I 
cannot stop laughing (bound to get flamed for 
this but here it goes anyway..) Super Saiyan 
Trunks ^-^