PG: Steve Nash
There is no question that Steve is the best PG in the game right now, you can stick him on any team and he will still rack up double digit assists. He sees the floor so well, generates chances for other people, and he can take over the game himself if he needs to score points.
SG: Dwyane Wade
I personally do not like Dwade, but I see what he is doing with that team and he is the best SG hands down right now. He is on a team of scrubs and the only other person who can compete with him is Kobe, and to be honest what Dwade is doing with the garbage he is with is much more impressive than what Kobe is doing with a team full of All Stars.
SF: Lebron James
This position is stacked with studs like Granger, Joe Johnson, Durant, and Melo and strong arguments can be made for all of them, but Lebron is a freak. Lebron commands so much respect on defense that he opens the floor for everone else on his team and he sees the floor so well. He is #5 in assists right now, which only Joe Johnson can compete with and still lags way behind. Lebron is the total package on offense and defense, there is no denying it.
PF: Dirk Nowitzki
Dirk is playing out of his mind, and again arguments can be made for guys like Bosh, but its hard to argue with a big who can strech the floor as well as Dirk and I have a soft spot for bigs who can shoot anywhere. He is playing great defense and the only thing I can really knock him on is I don't think he posts up enough to take advantage of his nice touch and size.
C: Amare Stoudemire
Amare is such a dynamic offensive player, people will argue for Dwight and I see why, but Amare has an all around game, he can pull up a jump shot, make his free throws, and spreads the floor better than Dwight. Right now Amare's season numbers aren't indicitive of his play due to recovering from injuries, but his December stats have been much better. His knock is his defense, but if you aren't watching the Suns this year he has played some great defense with his spacing, contesting shots, etc.