Vader #2 and Princess Leia #1
I was initially turned off by the first few Star Wars comics I picked up. But I got some more anyway... because Star Wars. Don't look at me like that... it's my weakness.
After two issues it's easy to say that Vader is a much better series than the main Star Wars comics. The Star Wars main comic feels very generic with too much action and not enough plot or character development.
Vader, on the other hand, is all about Vader's character development. It focuses on his relationship with the Emperor and his place in the Empire hierarchy. Since they're both Sith they don't trust each other and they plot behind each other's backs. It's really interesting. It has action too, but it's much more measured and intimating actions taken by Vader. It's not action for the sake of having action.
The Leia series is still a bit too early to tell. There's only one issue released and it eases into the premise of the story. I liked the set up and it seems like it's going to be an interesting character piece on Leia. It could end up being just as intriguing as Vader after another couple issues.