It's my belief that the NBA is more and more becoming a wing players league. With the extreme use of the three pointer, removal of shot blocking by way of the egregiousness of most charging calls, as well as the allowance of undercutting driving players, the center is fading away in the NBA. A great one is good to have, but a good one is great too.
As for power forwards there are a lot of stat fillers in the league, but Blake, when defended properly can easily be eliminated from a game, Love is awesome but can not take over a game. Davis is looking like the player to maybe buck the trend, but for now Duncan and Aldridge are the closest things to difference makers at the power forward spot.
Point guards, aside from our guy Rondo, are mostly merging with shooting guards, becoming score first players, the problem is due to their limited size, in crunch time of a playoff series they can be prevented from getting to the rim,
Now we're left with Lebron, Durant, George. You have to be realistic, if we're building a contender based around one player, that means your best player has to be able to beat a team built around Lebron and Durant.
This is the thinnest the NBA has been in a long time, after the top two there is a ridiculous drop off. I love Rose, Westbrook, Love, Aldridge etc. as much as any other NBA fan but those guys aren't going to win you a championship as long as Lebron and Durant are surrounded by real talent.
I wholeheartedly believe that the Pacers are the best team in the NBA, the worst part about it is I know that they will still lose to the Heat in the ECF. We all wish it wont happen, but deep down we know it will. Sure, seems a bit gloomy, but the honest answer to the original question, "List the number one players to build a contender around," yields bleak results.
1st. Durant
2nd. Lebron
Distant 3rd. George