So, let's say that GW really does make a compelling game, and brings older marks of Space Marines onto the table. Whether it's Unification Wars, Great Crusade, or Horus Heresy, it doesn't really matter, there are 18 Legions to choose from, along with two that are kind of up in the air that nobody really knows about.
Which would you build, paint, and bring to the table, and why?
Do you already have a Legion army?
Do you already have a Chapter or Warband modeled after one of the original Legions?
Though on the Chaos Side, Noise Marines are my favorite, Emperor's Children really don't strike me as a Legion I'd want to paint.
I'm thinking Raven Guard or Night Lords, especially if the rules end up making assault marines and stealth tactics viable.