I do like Greed, especially when he's in Ling's body. I like how Greed influences Ling into how to be a great emperor and Ling help him realize that his namesake was really a misnomer and that what he was really after was comrades and he had them. In other words, Greed had satisfied greediness all along.
Greed also is the only homunculus that doesn't follow his creator's ambition blindly and wants his own objectives met. He was talked into joining Ed and Hohenheim's small group of rebels against Father and King Bradley's regime.
Mine would have to be the 3 main Homonculi, Envy, Lust, and Gluttony (original series)
Envy- He is so cool and I like the twist that you find out in the end ( I don't want to spoil for people, but those who have watched should know what I am talking about) And I am not too sure if it is a girl or a boy so I just call him a 'he' because he looks more like a boy.
Lust- I like the way that she acts, and HER FINGERS/NAILS ARE SOOO COOL!!! I think the homonculi part would be nothing without her...
Gluttony- I just like him. The whole scary cannibal thing is really cool!!! (note: I know he isn't human but he looks like one so therefore he is a cannibal!)