Alonso's most outstanding characteristic is his speed and his ability to metre it throughout the race. He's not necessarily independent of the pitwall like Button; i don't think he's as wise or calm as Button anyway.
His speed enables the other skills to be used effectively. People don't look at Alonso as a speed demon for some reason, but the man can qualify and his race pace is monstrous.
What makes him the joint best, is how he meters his speed. We saw it in Korea. All drivers do this if they are fast enough or the car is good enough, But Alonso does it more dynamically. He's a good dictator as well (Hamilton doesn't do this, haters complain too much) and his driving is not affected by confidence or how bad the car is.
The only man faster, arguably, than Alonso, by a hair, is Hamilton. I honestly don't see Vettel or Kubica close to Alonso on speed.
He's the joint best IMO becuase of speed. If it wasn't, then his rating as the best would be subjective. Take away 5 tenth's off Alonso's speed and what are we left with? He's not really flashy or pugnacious on track; he just goes very fast.
I don't think Button needs a team to be built around him per say. 2009, it seemed pretty balanced with Barichello and Button did very well. Button doesn't even need to be vocal and direct the team like Alonso to be top dog. What he needs is to be the flagship driver. The only way that happens is if his teammate is slower.
It's just not going to happen at Mclaren. Speed is everything there.
Mclaren had some pretty outrageous and colourful drivers over the years.
Senna, Prost, Lauda, Hakinen, Raikonen, Coulthard, Hamilton, Alonso, Montoya
What do these guys have in common? RAW SPEED.