The first (well, the first two) had a genuine, organic sense of humor.
STAR WARS: "I'm Luke Skywalker and I'm here to rescue you."
EMPIRE STRIKES BACK: "I love you." "I know."
RETURN OF THE JEDI has a real "let's get this done and collect the check and wrap it up" mentality. Bad story. Leia would have made the better Jedi.
The 1999-2005 installments are just so incredibly heavy. There's no sense of humor that feels genuine.