My all time favorite character in Lost is probably Ben Linus. Why, because he is very interesting, a combination of good and evil. Sawyer is a great developing character too. Daniel Faraday is an interesting character also, with his personality and how he deals with stuff. I was dissapointed by how Desmonds character was used in season 4, he doesnt seem to get much attention and in "The Constant", his character seems out of control. Micheal made a great combat, definetly making his personality alot more likable. Locke was also dissapointing too. He seems too obsessed by finding out the answers instead of being a caring person like in season one and two. Bernard and Rose are just great characters, really nothing bad to say about them.
These are my opinions, but what are yours?