Its all about your personal preference. I love 09 Charbon, with GH, not so much with RH though. Since you're interested in RH, I would suggest Granny, Maldives, or Mandarin. You never really know which color will be the next "must have," instead buy what YOU love.
It's so hard to vote when the fall collection hasn't even hit the stores! But if I have to pick one (or two), it will be the upcoming pourpre and tempete. These are totally my colors, so my opinion is biased.