I'm thinking it may be the Sears Tower, Empire State Building or Chrysler. Or it could very well be the Equitable Building with a FAR of ~30. It's not merely being tall as any site that includes a plaza area will significantly impact the FAR calculation.
I found an interesting link on the topic: https://www.planning.org/pas/reports/report111.htm
. It says the Empire State Building has a FAR of 32, which sounds about right. Then it goes on to list the Equitable Building as 17 and that's way off.