Frankly I kinda hate Heero because he's just terrible! Duo is the coolest among all the characters. Don't know why, but I think he's the cutest and the nicest among them
The series is good, even if I'm not really into it and I haven't watched all the episodes. The female characters are probably the worst I've ever seen in an anime series based on mechas, but since the attention is focused on male characters, I don't really care.