From my sofa, Sierra had very little power after the merge, but it's always a good idea to break up couples.
Sue is far and away the weakest player thus far, and the only one I can't see winning it all. She is a good bet to make the final 3 for that reason. Andy is a hard read because of his personality, but he is playing, and I hope he keeps his demons at bay so it continues. Gabe is someone who needs to make some things happen, but I need convincing that he is capable of doing that. Teeny is not in my bottom four, but if she belongs there, it's only because this is the deepest season of strong players that I have ever seen.
For me, Rachel, Caroline, and Genevieve are at the top, with Sol and Teeny not far behind. My worry for Sol is that he clearly has a thing for Rachel, and it may impact his game.
Kyle is a challenge whore, but it's not clear whether he has a social game. We likely won't have the chance to find out, as he is probably gone if he ever loses an immunity challenge. In that scenario, he could end up being a swing vote for someone in an "anything to stay in the game" type of deal.
Sam is an unknown quantity at this point. Does he have any game without Sierra calling the shots? Time will tell. I would love to see Andy use him as a number until it no longer suits him.