Each has its own set of pros and cons, but I guess none is better than the other.
The leaf spring takes the form of an arc-shaped length of strong steel bars, with some loops connected to the car chassis. The more the vehicle weighs, the more "leaves" or "steel bars" are stacked over each other. Often, the length of the leaf or bar is progressively shorter.

Coil springs, on the other hand, use a spring and are placed at the top of the car axle or chassis and at lower the control arm. They deliver more movement than a leaf spring and can be modified or tuned to one's liking. Coil springs are also preferred for high-performance vehicles as they can provide the driver with a wider turning envelope across the suspension range compared to the leaf spring suspension model.

Here are FAQs about leaf spring and coil spring. If you have any other concerns, please feel free to comment below. I'm going to answer anything if I can

Q: Which suspension type is best suited for carrying heavy loads?
A: Leaf spring suspensions are better for carrying heavy loads.

Q: Why are leaf spring suspension cars less comfortable?
A: This is because the leaf springs are tighter and have less range of motion than the coil spring suspensions.

Q: What is the most common problem with leaf spring suspensions?
A: Both leaf and coil springs sag with age.

Q: How long do coil springs last?
A: It depends on how one uses a car, although some of them have been known to last for a very long time.

Q: Which suspension type is the best one for a track car?
A: Coil springs are best suited for high-performance applications such as racing because they are more tunable and can provide better handling.