Siddle is a trier, but doesnt have to tools to be the worlds best bowler, he is above average pace, fairly accurate, occasional swing and firey temperament. Hughes has to show that he can score runs at Test level on more than one type of pitch, he has failed when the ball showed the slightest bit of sideways movement. Johnson is no doubt a great talent, and has all the attributes to be one of the worlds best.
Bopara is no doubt a great talent, but he seems to so far lack the metal attributes to hang with the worlds best.
Bell also has great talent, that cannot be denied - however it doesn't seem he will ever fulfil his potential. Just doesnt score enough runs.
Broad has just gone 23.He is nearly 2 years younger than Peter Siddle, bowls around the same pace, gets more bounce and is a far superior batsmen. At the moment he is nowhere near as good a bowler as Siddle, but he could be. He has more raw ability to boot.
Cook is a 24 year old with 3430 runs at 44.5 in test cricket. Not sure how he is average - thats above average already with room to improve.
As you said before, being biased towards our respective countries we are inclined to believe in our players more. To be honest i see our boys as above average at best and your players as being the same. Neither will amount to superstars.