Although Star Wars is my favorite movie (of all-time), I will say that Empire is the better movie. Sort of like when I compare Tarantino's Resovoir Dogs to Pulp Fiction, I love Dogs more but Pulp is the better movie overall.
Now in fairness, Star Wars and Empire are two different types of movies. Star Wars is essentially a fantasy serial that isn't supposed to take itself too serious, as it resembles a movie like Wizard of Oz. Empire IS supposed to be serious, (hence the Cave scene). That scene is what seperates Empire from the other 5 SW movies because it isn't spelled out for the viewer and there is alot that is going on if you watch it over and over. What Lukes does BEFORE he goes in the cave, what Luke does during the cave, and Yoda's quiet reaction as Luke has failed at the cave. Many PT gushers argue the PT has alot of symbolism like the cave scene, but it is all tricks and cheap lines like Obiwan saying to Anakin in Clones, "You'll be the death of me." Well of course Lucas knows that when he is writing it because he's seen the OT!
I think SW & Empire accomplish what they set out to do, and what you see over the next 4 SW films is Lucas trying to mend SW and Empire together and it just doesn't work. Jedi & Menace try to be like SW on a grand level, yet try to be empire on a smaller level. Clones and Sith try to be like Empire on a grand level, and try to be like SW on a smaller level.