My favourite character would definitely have to be Elrond... but only for his eyes. To me hugu only really got elronds character in the council of elrond and he seemed a little too emotional in other parts of the movie.
Orlando, for me, portrayed legolas terribly! He exaggerated his abilities too much and he only said things like " a shadow and a threat has been growing on my mind...", " 44, 45, 46, 47...62, 63, 64... how many gimli?! etc." and re-stating the obvious. He's my choice for worst character... and eowyn, she has funny expressions and is whiney... it's only my opinion...
Karl urban really got eomer's character and give him lots of credit. he was really good at his reactions and made a really convincing rohirrim... he's my pick for best character