Please don't go back to vintage or POTF2 for the worst, because we all know there were some bad ones.
Best: Episode 2 Palpatine. That thing is pure plastic witchcraft. Simply the best likeness I have EVER seen in plastic. Not only did it capure his exact likeness, but also the sinister, maniacal nature of his character.
Worst: This is tough, I was going to go with any and every Qui-Gon ever made. They were never even close. He has such distinguishing features, but they failed to utilize any of them. Also, they loved to sculpt him screamig even though he was one of the most calm and composed characters in the film series.
Then I thought about that rat looking Luke X-wing. Hmmmm
Then I came to to a decision. It's not because it is a particularly BAD sculpt, but it was a VERY BAD choise of facial expressions. You all know what I'm talking about...
What do you guys think?