Height is a whole different thing than appearance.
I'm sure there were many people who (before Taipei 101) thought 'Hey, the Petronas Towers. Wow. That's one big ass motherf*cker of a building. Its even taller than Sears!!!'
What I mean is quite simple. Look at the diagrams of the current WTBs.
Compared to the Sears Tower, the Petronas Towers are actually looking 'small' and skinny!
Their spire increased height gives the impression of being massive. But they aren't! Sears is a much more hulking heavyweight than the two Petronas twrs together. It's the same with Taipei 101, which is pretty skinny at the Top.
Height for itself can only be a numeric criteria for comparison. In the end, it all depends on the individual apperance and bulkyness of a building.
To stay in Chicago, the Chicago Spire could become a stick insect compared to Sears, even if it's much taller.
Same for the NYC-Chicago battle. Sears will always be taller than 1WTC, and will have much more mass, of course. A spire that reaches 1776ft will not help. In terms of apperance, that is.
I hope you can figure out what I mean. Giving auch explainations is definitely not my thing.