Best choice for stability...

[Apolan]

What i imagine under the term "stable" is that a car isnt twichy, isnt loosing ground over bumps, has a neutral balance, good grip with minimised roll and that you can feel the outputs of the car, making the ride predictable and comfortable to push hard. That would mean you need to know where you'll be driving and how. When rallying stiff springrates will make the car bouncy, when on track, soft springs will make the car roll alot and throw you all over the place.. So ther is no optimal solution for all aplications. Only the best aproximation to ones needs.