I've owned both, well a Metallica Pro which I sold and now a Star Wars LE. Metallica didn't hold me long due it's ruleset design which feels like a grind. I prefer objective based rulesets and while Metallica has some objective based modes (Crank it Up modes) they are locked behind grind based objectives (hit target 10x, 20x, etc) that get old quick in my opinion.
Star Wars on the other hand is one of Sterns most deepest objective based games with a story based ruleset covering the entire original trilogy. There are so many different ways to play Star Wars as well with the character / ability select and then deciding which of the 4 locations you want to go through.