Good question, but I don't think there is a straightforward answer. First of all, one has to define what a "good handling car" is. In my mind, there can be several answers:
1) A good handing car is a car that can be defined as having very high grip when turning or changing directions........usually this can be measured by parameters such as how many g's a car can pull on a circular skidpad, how fast a car can go through a slalom, or how fast it takes to complete a test like Motortrend's figure 8 test. Laptimes on a short tight technical track/road coarse can also be indicative of how fast a car can turn through corners, which is again a measure of cornering grip. The faster you can take a corner or turn without understeer/oversteer, the better "handlng" the car is. Remember, you don't see F1 cars sliding in the corners because it is NOT the fastest way around a corner.
2) Alternatively, a good handling car can be defined subjectively by how it "feels" to the driver when turning or changing directions rapidly. Usually, good tactile steering feel along with the ability to place the car accurately with the steering, less body roll (feels you're "cornering on rails" or "like a go-kart"), and less understeer (which is part of definition #1 above) are all things that can inspire confidence to the driver that the car can be pushed through the corners more aggressively......whether this actually translates into faster cornering speeds with higher cornering grip is questionable and depends on the car.
3) Another definition can refer to how controllable/adjustable a car is after you have breached the grip limits of the car. We often see videos of journalists/drivers pushing the cars beyond the grip limits of a car, usually with power oversteer out of turns. Many journalists then praise a car if they can sustain such a slide with a combination of throttle and steering inputs.......if the car is well "balanced", such a feat is easier, can be consistently done, and supposedly very enjoyable.
You would think that a car that has all of the above would be "perfect" from a handling point of view. However, this also may not be case for some people. If a car has tremendous objective grip, then sometimes it gets "criticized" because the limits are so high so you can't explore definition #3 above unless you corner at insanely high speeds.
So a good handling car may mean a different thing to different people. Frankly, it depends what you enjoy or value most. Personally, I never deliberately want to or regularly enjoy definition #3 above on the roads or on a road course. I prefer a car which excels at definitions #1 and #2. I suspect not many drivers regularly power oversteer out of turns, even though so many journalists want to praise a car because of definition #3.
