None of the numbers are a great substitute for driving them but if you made me pick one it'd be slalom speed/time. That gives some idea of how quickly a car transitions and how easy/hard it is to drive near the limit.

 

I like to look at front/rear balance(50/50 best), total weight(lighter better), chassis stiffness(hard numbers to get but stiffer is better), steering turns lock to lock(fewer better) and steering ratio( lower better)for clues at how a car might respond and feel when you ask it to turn. Which to me is what handling is about.

A skidpad number is partly dependent on handling but mostly depends on tires so I don't think it tells as much about handling by itself.

But as most point out you have to drive a car to see how all the elements actually fit together for your purposes.

 

Most of us don