I think going in that John Wall has to be the favorite for Rookie of the Year, but not just because he was the number one pick - here are three reasons I think he wins:

1. As a guard, I think he has a smaller transition from college to the pros. Favors or Cousins could actually turn out to be a great pickup in a few years, but it always feels like centers and forwards take a few years to develop (just compare Joakim Noah and Derrick Rose - Noah is contributing, but it took a couple years while Rose jumped in and adapted right away).
2. Wall is going to Washington - without the insight of who any of these teams might pick up in free agency, I think Washington provides the best spot to shine (especially if Arenas plays to his potential. Wall has the ability to go to a team where he can be a star, but also has a player or two to work with. The other teams either have almost no help (e.g., Turner to the Sixers) or the player won't be able to shine as much (e.g., Johnson to Minnesota).
3. He was the number one pick, right? You have to think that if there was someone else who was the favorite to be the rookie of the year, Washington would have taken them number one.

The rookie of the year will likely be Blake Griffin. The reason for this is that non of the players mention before has a year of NBA experience. There is something to be said for being around the league for a year even if a player does not play a single minute. Blake is eligible even thought he was the first pick selected in the 2009 NBA draft with the number one overall pick by the Los Angeles Clippers, because he did not play a single minute in the 2009 and 2010 season. This loop hole should help Blake to become the NBA’s rookie of the year in 2010-2011. John Wall will probably have the biggest impact on his team this year based on the five names mentioned in your question, simply because he is the most talented of those players listed.